Chapter+2

= =

1 =**SECTION 1** = toc = =
 * Homework 11-7-10**
 * http://www.sciencedaily.com/releases/2010/09/100902073509.htm**
 * Summary:**
 * Roberto Carlos' had kicked a free kick goal against France in 1997 and it was thought to have been the most skillful free kick goal. A group of French physicist, have computed that the kick was no fluke. The research shows that the French goalkeeper made no move to the ball as the ball made a last moment sweep left and landed in the back of the net. The french researchers used tiny plastic balls as a slingshot and they varied the velocity and the spin of the balls traveling through water to trace the different trajectories. They research confirmed the Magnus effect, which gives a spinning ball a curved trajectory, the research revealed insight for spinning balls that are shot over a distance around Carlos' free kick. The friction that is exerted on a ball by its surrounding atmosphere slows it down enough for the spin to take on a greater role in directing the balls trajectory. The allows for a last moment change in direction, which is how he ended up scoring the goal. The researchers call this discovery the spinning ball spiral. The reason that Carlos shot the kick from such a far distance was because he had reason for doing to so, knowing that it would change directions and go on**

They are able to move across the ice,because there is not a lot of friction so the skater is just able to move across the ice without having to exert a lot of effort. The momentum that is there is going to cause the skater to keep moving. When they accelerate to a certain velocity the mass allows them to keep moving. It continues to roll across the field after it had been kicked because, the amount of force that has been applied causes the ball to continue moving. Once an object is in motion there had to be an opposite motion to stop it from moving.
 * What Do You Think?**
 * How do figure skaters keep moving across the ice at high speeds for long time while seeming to expend no effort?**
 * Why does a soccer ball continue to roll across the field after it had been kicked?**

1 c. 4.45 1 e. 4.45 2 a. it will go to the same point that it did before 2 b. because it is starting from the same initial point 3 a. My prediction was correct because he kept going to the same height each time. 4 a. I think the skater will go higher on the side that I lowered because when he gets down the higher slope he gains more momentum causing him to go over the lower slope. 4 b.I was correct because the skater traveled off of the track due to the fact that it was significantly lowered. 5 a. No because the line is vertical and the ramp does not go back up in height, for it to move back up. 5 b. I think the skater would roll far because he would have a lot of momentum and only a small slope to travel up. 5 c. It would roll until something else acts upon it and would keep its momentum, which would keep it rolling. 5 d. It will travel on the track for forever. 6 a. The length will be increasing. 6 b. The height that it reaches is the same as the height that it started at regardless of the slope. 6 c. Both of the heights will be equal. 6 d. It would never stop and travel for forever.
 * Investigation X1:**


 * Physics Talk Notes**
 * Summary:**
 * Galileo is also called the father of modern science.
 * He saw that a ball that rolled down a ramp seemed to eventually have the same height when it rolled up another ramp.
 * He created the law of inertia- the natural tendency of an object to remain at rest and to remain moving with a constant speed in a straight line.
 * A force has to act upon it to be able to stop the object.
 * Newton- used law of inertia as the basis for the first law of motion
 * First law of motion: In the absence of an unbalanced force, an object at rest remains at rest, and an object already in motion remains in motion with a constant speed in a straight line path.
 * Sometimes speeds are constant.
 * Objects in motion stay in motion unless a force acts upon them.
 * speed- the change in distance per square unit
 * velocity- speed in a given direction
 * acceleration- the change in velocity per unit of time
 * frame of reference: a vantage point with respect to which position and motion may be described speed is relative to something
 * depends on the reference point that you are talking about. (example of being on a plane, cant tell you are moving unless you look out the window to see) in less you changed direction/ accelerated then you can tell that you are moving.

**Inertia is a property of matter that measures the resistance to changes in an object motion.** **Mass is how we measure inertia (kg is the base unit)** **Weight is how much gravity pulls on a mass.** **You cannot just continue to keep going, because friction stops you from keep moving up.** **A running start allows you to get more speed, then you were initially going to get. (example of dropping something out of the car, it is the same speed that you in the car are moving, and then it eventually it stops and it will slow down)** **A running car increases the speed** **Body has inertia -- plane example when taking off.**

property that measures the resistance to changes in an object motion in the absence of an unbalanced force, an object at rest remains at rest, and an object already in motion remains in motion with constant speed in a straight-line path. (Things wont change there motion unless they are forced to do so) A force needs to act upon the motion in order to stop it from moving at constant. <span style="color: #000000; font-family: Arial,Helvetica,sans-serif;">The frictional force that is between the ball and what it is rolling on. <span style="color: #000000; font-family: Arial,Helvetica,sans-serif;">The object that has greater mass. The frame of reference is important because you need to have a relative. It has to do with the respect to which position and motion may be described.Reference to you, or the train
 * 1. What is inertia?**
 * 2. Describe Newton's first law of motion.**
 * 3. What needs to act on an object to stop it from moving at a constant speed.**
 * 4. In the real world, a rolling ball does not roll forever. What stops the motion of the ball?**
 * 5. Given two different size masses moving at the same speed, which mass will have the greater inertia?**
 * 6. You throw a ball in a moving train. Why is it important to establish a frame of reference when describing the speed of the ball?**

**PTG #1-4 and 10, p 143** 1 a) the ball will travel until another force acts upon it. b) it will continue to travel for forever because newtons first law of motion states that if there is an object already in motion it will remain in motion with constant speed on a straight line if there is an absence of an unbalanced force. 2) 20 cm, it will reach back to what its original height was. 3) I do not think it is possible to arrange things to be unassisted and move in a straight line forever because there will always be an unbalanced force acting upon it and there will always be some sort of interruption eventually and could not run for forever. Everything has at least a little bit of friction. 4) the puck is traveling at a very fast speed after it is hit until another force acts upon it, the other force is the friction of the hockey stick stopping the puck. Because in this scenario the puck has not hit the stick yet it would still be traveling at the very fast speed. 5) 7 m/s 6) 14.5 m/s

7) a) 8 m/s (add the speeds) b) 3.2 m/s c) 6.1 m/s @ 67 degrees 8) 67 m/s 9) a) 21.2 cm  b) 43.9 m/s c) 58 cm d) 172 m/s



10) a) baseball: the glove stays at rest, while the is stopped when it is caught inside the players glove. lacrosse: the lacrosse stick stays in motion and catches the lacrosse ball in the net. soccer: the goalie catches the ball in his gloves, while the ball is moving and this causes the ball to stop. these balls were not going to change their path, but they were forced to do so. b) the baseball would be caught by the player lacrosse

**How do figure skaters keep moving across the ice at high speeds for long time while seeming to expend no effort?** They are able to move across the ice because that there is little friction on the ice. A force does not stop moving until something is acted upon it, so because that there is friction it does not stop moving. **Why does a soccer ball continue to roll across the field after it had been kicked?** It continues to roll across the field after it had been kicked because, the amount of force that has been applied causes the ball to continue moving. Once an object is in motion there had to be an opposite motion to stop it from moving.
 * What do you think now?**

<span style="font-family: Arial,Helvetica,sans-serif; margin: 0px; padding: 0px;">**Inquiring Further** <span style="font-family: Arial,Helvetica,sans-serif; margin: 0px; padding: 0px;">**Curling and Newton’s first law** <span style="font-family: Arial,Helvetica,sans-serif; margin: 0px; padding: 0px;">**- Find out about a sport called curling. It is an Olympic competition that** <span style="font-family: Arial,Helvetica,sans-serif;">**involves some of the oldest Olympians. How can this sport be used** **to illustrate Newton’s first law of motion?** Because of the friction, curling is a good illustration of the first law of motion. The object continues in a straight line motion until it comes in contact with another object. This stops the original force that acted upon it. <span style="font-family: Arial,Helvetica,sans-serif;"> http://www.curldc.org/about/ = = =SECTION 2= What do you see? In the top picture the boy is slowly walking home from school at a constant speed, while in the second picture the boy is running in a rush with flowers at constant speed in a hurry.

What do you think? 100 mi/h means that if the ball was traveling for 1 hour it would travel at a speed of 100. 45m/s means that if the ball was only traveling for 1 second it would travel at a speed of 45.

At a constant speed the distance between the ticks are equal in length. When traveling slow the ticks were shorter than when you traveled at a fast constant speed. At fast, the ticks are longer because a greater distance was covered. When a person is accelerating the distance between the dots on the tape were not equal. Acceleration is the change in velocity of an object over time. Speed is a ration of distance traveled to the time taken. Average speed is the distance traveled divided by the time it took to travel to that distance. Instantaneous speed: the speed measured during an instant, the speed as the time interval approaches but not become zero. average velocity- the rate at which a distance is traveled or the rate that a position changes. a= change in velocity/ change in time= vf-vi/t same as Vf= vi+at for **velocity** usually m/s or km/h or mi/h are used. for **acceleration** use m/s^2 When the signs of velocity and acceleration are the same it is **INCREASING** speed. When the signs of velocity and acceleration are opposite it is **DECREASING** speed.
 * Physics Talk**

<span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> **Checking Up Questions** <span style="font-family: Arial,Helvetica,sans-serif;">1a. constant speed is the distances between ticks were equal length <span style="font-family: Arial,Helvetica,sans-serif;"> 1b. positive acceleration is when gradually increasing the speed, the distances between the dots gradually got longer <span style="font-family: Arial,Helvetica,sans-serif;"> 1c. negative acceleration is when gradually decreasing speed, the distances between the dots gradually got shorter <span style="font-family: Arial,Helvetica,sans-serif;"> 2. Vav = change in d / change in t, Vav = 400m / 50s, Vav = 8 m/s <span style="font-family: Arial,Helvetica,sans-serif;"> 3. instantaneous speed is the speed of a at a certain time. (must smaller time interval) <span style="font-family: Arial,Helvetica,sans-serif;"> average speed is the average speed of the entire trip. <span style="font-family: Arial,Helvetica,sans-serif;"> 4. Vf=v1+at 100 km/h=0 km/m =2.8 m/s

<span style="color: #000000; font-family: arial,helvetica,sans-serif; font-size: 16px; line-height: 23px;">Physics To Go

<span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> 1. In your own words, compare average speed and instantaneous speed.
 * Average speed is the speed that is averaged over a period of time. Instantaneous speed is the speed at any particular time.**

<span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> 2. Calculate the average speed in each of the following situations. <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> a) A horse runs 1 km in 15s <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;">**66.6 m/s** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> b) A skier travels 84 m in 6s <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;">c) You walk 9.6 km in 2 h <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;">**4.8 m/s** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> d) A car travels 400 km in 4.5 h
 * 14 m/s**
 * 89 m/s**

<span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> 3. In which of the following cases is acceleration occurring? If acceleration is occurring, indicate if it is positive or negative. <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> a) A runner falls down- **Negative Acceleration** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> b) A runner takes off from a starting block- **positive acceleration** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> c) You walk down a straight hall at a steady speed- **no acceleration** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> d) A soccer ball is caught by the goalie- **negative acceleration** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> e) A bowling ball rolls along the gutter at a constant speed-**no acceleration** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> f) A parachutist falls at constant speed- **no acceleration**

<span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> 4. You have measured speed in terms of the length of paper tape. A quick and portable way of representing the paper tape graphs you made is by drawing graphs of the data. The four graphs labeled a-d are histogram.s Each bar on the histogram represents a piece of the cut paper tape. <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> a) Which graph represents a student moving with a constant increase in speed? **A,D** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> b) Which graph represents a student moving with a constant speed? **B** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> c) Which graph indicates the greatest change in speed each second? **A** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> d) Which graph represent the motion of a student whose speed first increased but later decreased? **C** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> e) The acceleration of an object is defined as the change in speed of the object per second. What is the acceleration of the student in A, B, C, D? **A- positive acceleration B- no acceleration C- positive and then acceleration D- positive acceleration** (work for problems below) 6. -1.4 m/s^2 vf-vi/ t b) negative 7. a) constant b) increasing c) slow constant, increasing faster but constant, slows downs back to constant.d) decreasing constant and then increasing. 8. 50 mi/h 9 No, instantaneous is the speed at that exact second. 10. X.X..X...X...X....X = accelerating X...X...X...X = constant 11. 4,8,12,16,20 m/s (adding 4 every time)

<span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> 14. Describe the situation during sports event that might produce ticker tape patterns similar to the ones you produced in the investigate. <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> a) constant motion at an average speed- **If you kick a soccer ball on the ground at a constant speed.** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> b) constant motion at a fast speed- **If someone were ring in t in.** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> c) constant motion at a slow speed-**In curling with the stone** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> d) positive acceleration-**Runner trying to reach a base in baseball to score.** <span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;"> e) negative acceleration- **Runner changes direction, basketball to score a basket.**


 * Physics Plus**
 * **velocity** || **acceleration** || **example** ||
 * small || small || turtle ||
 * big || big || race-car, airplane, rocket ||
 * small || big || rabbit, dog, deer, rebounding (any object) ||
 * big || small || truck ||
 * **Rebounding is when you change direction.**
 * **Even if the speeds are small,accelerations can still be huge if the bounce times are tiny**

3) a,b,c= -5 m/s and Linear because acceleration is constant for the entire trip.

<span style="color: #000000; font-family: arial,helvetica,sans-serif; line-height: 19px;">** What do you think now? ** **100 mi/h and 45 m/s are both average speeds or instantaneous speeds. They are measurements of velocity, they measure distance in relation to time. You could find velocity by dividing distance traveled by the time that has passed.**

=**SECTION 3**=

What do you see?
 * I see a person pushing a ball with a stick and they start out at a slow speed. They then begin to move faster. The ball is staying right near the stick. At first its easy for the dog to keep up but then it keeps getting harder and harder.**

What do you think?
 * What is a force:** a force is either a push or a pull, strength or energy exert force.
 * How will the same amount of force affect a tennis ball and a bowling ball differently?** A tennis ball will have more force because it has a smaller mass and a bowling ball with have less force because it is heavier, and needs more force to be able to move.

<span style="font-size: 16px; line-height: 23px; margin: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 5px;">Physics Talk

Summary: **A constant force produces an acceleration. Acceleration decreases with an increase in mass. Newtons second law of motion states that the acceleration of an object is directly proportional to the unbalanced force acting on it and is inversely proportional to the objects mass. As a force gets larger the acceleration gets larger which is why is is a direct proportion. Acceleration = force/mass. Accelerations are caused by unbalanced forces. Acceleration gets less and less as the mass gets larger. W<span style="font-family: Arial,Helvetica,sans-serif;">hen two forced act at the same time, the direction as well as the magnitude of the forces determine the motion of the object. The the forces are in the same dirction, then the sum of the forced or net forcecould be zero and there would be zero acceleration. Free-body diagram: a diagram showing the forces acting on an object **

**1. Describe Newton's second law of motion in your own words**. The acceleration of an object is directly proportional to the unbalanced force acting on it and is inversely proportional to the object's mass. The direction of the acceleration is the same as the direction of the unbalanced force. **2. For a constant force, what effect does increasing an object's mass have on its acceleration?** increasing an object's mass when a force is acting on it, the acceleration will be smaller. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 12px;">**3. If an object weighs 30 N. Weight is the vertical donward force exerted on a mass as a result of gravity. The force is 30 N.** <span style="font-family: Arial,Helvetica,sans-serif; font-size: 12px;">**4. On a planet with a higher acceleration, your weight would increase, but your mass would remain the same.**

Physics To Go <span style="font-family: Arial,Helvetica,sans-serif;">**1. a) 350N** <span style="font-family: Arial,Helvetica,sans-serif;"> **b) 80kg** <span style="font-family: Arial,Helvetica,sans-serif;"> **c) 10m/s^2** <span style="font-family: Arial,Helvetica,sans-serif;"> **d) 80kg** <span style="font-family: Arial,Helvetica,sans-serif;"> **e) -15m/s^2** <span style="font-family: Arial,Helvetica,sans-serif;"> **f) -3000N**

<span style="font-family: Arial,Helvetica,sans-serif;">

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">3. What is the acceleration of a .30kg volleyball when a player uses a force of 42N to spike the ball? **F = (m)(a) ; 42N = (.30kg)(a); a = 140 (m/s)/s** <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">4. What force would be needed to accelerate a .040kg golf ball at 20m/s^2? **F = (m)(a) ; F = (.040kg)(20m/s^2) ; F = 0.8N** <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">5. Most people can throw a baseball father than a bowling ball, and most people would find it less painful to catch a baseball than a bowling ball flying at the same speed as the baseball. Explain these two situations in terms of <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> a) Newton's first law of motion- **A bowling ball has a larger mass than a baseball, so it has more inertia, because it is heavier. The baseball has less inertia but it will also travel in the same straight line movement for longer because its lighter so its easier for humans to accelerate it.** <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> b) Newton's second law of motion- **Mass an acceleration are indirectly proportional. The baseball has less mass will have greater acceleration. It is going to go faster when it hits your hand. The bowling ball will not go as fast.**

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 9. You throw a ball. When the ball is many meters away from you, is the force of your hand still acting on the ball? When does the force of your hand stop acting on the ball? <span style="color: #000000; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">﻿**Yes the force of your hand is still acting on the ball, keep acting until an unbalanced force.** 10. Carlo and Sara push on a desk in the same direction. Sara pushed with a force of 50 N, and Carlo pushes with a force of 40 N. What is the unbalanced force acting on the desk? The unbalanced force on an object is sometimes called the total force, or net force, on an object.
 * The unbalanced force is friction. If no friction was present then you will need very little force to push the desk. The friction makes it harder to push the desk, force must be applied.** **50N + 40N = 90N**

11. A vehicle is stuck in the mud. Four adults eachpush on the back of the vehicle with a force of 200 N. What is the combined force due to all four adults, on the vehicle? **The combined force is 200 x 4 = 800 N of force being pushed on the back of the car. The total combined the net force is 4 times 200, which gives you 800 N, this is what you need to be able to get the car out of the mud. There can also be opposing forces that are acting as well.** 12. A baseball player throws a ball. While the 700.0 -g ball is in the pitcher's hand, there is a force of 125 N on it. What is the acceleration of the ball? 15. The acceleration due to gravity at the surface of Earth is approximately 9.8m/s^2. What force does the gravitational attraction of earth exert on a 12.8 kg object, such as a toolbox loaded with tools? **F=mg=** **F=(12.8kg)(9.8m/s^2)** **F= 125 N** 18. Using a sport of your choice, write a script for a voice-over that deals with accelerated motion and forces.
 * F=am**
 * 125N =a(.7kg)**
 * 179 m/s^2**
 * The first base man is getting ready to throw the ball to home plate to get the runner out. He is moving his arm back to get more acceleration on the ball. There is going to be more force to allow the ball to get the home plate.**

130N at 67 degrees NE 6403 N at 39 degrees 8.9 m/s^2
 * 13. During a football game, two players try to tackle another player. One player applies a force of 50 N to the east. A second player applied a force of 120 N to the north. What is the resultant force applied to the player being tackled?**
 * 14. In auto racing, a crash occurs. A red car hits a blue car from the front with a force of 4000 N. A yellow car also hits the blue car from the side with a force of 5000 N. What is the resultant force on the blue car?**
 * 16. A force of 30 N acts on an object. At right angles to this force another force of 40 N acts on the same object.**
 * a) What is the net force on the object?**
 * 50 N at 53 degrees **
 * b) What acceleration would this object have if it is a 5.6 kg wagon?**
 * 17. Bob exerts a 30 N force to the left on a box (m=100kg). Carlo exerts a 20 N force on the same box perpendicular to bob's force.**
 * a) What is the net force on the box?**
 * 36 N t 24 degrees **
 * b) Determine the acceleration of the box.**
 * . **36 m/s^2
 * c) At what rate would the box accelerate if both forces were to the left instead of perpendicular to each other?**
 * .5 ** m/s^2



PHYSICS PLUS **What do you think now?** Force is a push or a pull Mass and acceleration are indirectly proportional. With the same force, the bowling ball, which has more mass, would have a smaller acceleration. The baseball, with a smaller mass, would have a greater acceleration.

=SECTION 4=

What do you see? What do you think? What determines how far an object thrown into the air travels before landing?
 * A person standing on a small ladder and they are throwing apples, either straight down or straight out, then moving down. They all see to be equally spaced out. The person under seems to be timing how long it takes for them to hit the ground the differences between them.**
 * It depends how much force they are being thrown with. It also depends the timing when the person dropped it and how there arm was placed.**


 * Physics Talk**
 * Trajectory- path**
 * projectile- an object acted on only by gravity**
 * The x and y component of all vectors are independent**
 * ex- (y) vertical velocity affects vertical distance**
 * (x) horizontal velocity affects horizontal distance**
 * The time that it takes for a horizontally launched projectile to reach the ground (hang time) is the same as the time it takes to drop.**
 * Acceleration due to gravity is -9.8 m/s^2 [negative because gravity always pulls down]**
 * Vertical velocity changes by -10 m/s every second.**
 * Horizontal velocity never changes**
 * Vy is always 0 at maximum height.**
 * throwing horizontally results in the same trajectory as the second half of a ball thrown at an angle**


 * checking up questions**
 * 1. yes they will reach the ground at the same time, because with the exception of air resistance and acceleration is acting upon them at the same time, with the same rate**
 * 2. The velocity does not remain the same, because it increases about 10 m/s every second**
 * 3. The balls velocity is at highest is 0, and the acceleration is still -9.8 m/s^2**


 * INVESTIGATE**

I asked my family and friends and they didn't think that a bullet would hit the ground at the same time. They though the shot bullet would hit the ground first. I also asked them about the pennies, and they thought it would be the same time. It seems that just the idea of it being a bullet, people don't think that it would be the same time.
 * PHYSICS TO GO**
 * 1. Draw a sketch of two coins leaving the table. Show where each coin is at the end of each tenth of a second. Remember to emphasize that they both hit the ground at the same time. **
 * 2. Repeat the sketch of the two coins leaving the table, but this time have one of the coins moving at a very high speed. **
 * 4. Survey your friends and family members to find out which they think will hit the ground first, a bullet that is dropped, or a horizontally shot bullet. **
 * Explain why you think people may believe that the two coins hit the ground at the same time, but that they have a more difficult time believing the same fact about bullets. **
 * 6. Use evidence from your observations of the ball and chair in this section to show the truth of the statement "A projectile's horizontal motion has no effect on it vertical motion, and vice versa.**"A projectile horizontal motion has no effect on its vertical motion and vice versa, because vertical velocity changes by 10 m/s every second. Horizontal does not change it remains the same**.**


 * 7. Look at the diagram of an arrow being shot horizontally from a bow and another arrow dropped from the same height. Arrow A is shot horizontally at a speed of 50m/s. A second arrow, B is dropped from the same heigh and at the same instant as arrow A is released. Neglecting air friction, how does the time A takes to strike the horizontal plane compare to the time B takes to strike the horizontal plane?** A and B will hit hit the ground at the same time. They are both dropped or shot in the air from the same height.


 * 8. A swimmer jumps into a river and swims directly for the opposite shore at 2 km/h as shown. The current in the river is 3 km/h and flows from left to right in the diagram. What is the swimmer's velocity relative to the shore?** 113.01 m/s


 * 9. A football is thrown at 15m/s at an angle of 37 degrees in the horizontal direction.**
 * a) What is the velocity in the horizontal direction? 11.3 m/s **
 * b) How far in the horizontal direction has the football traveled in 2 s?** v=d/t 11.3= d/t d= 22.6 m
 * 10. A shot put is released at 12 m/s at an angle of 45 degrees in a horizontal direction.**
 * a) What is its velocity in the horizontal direction? 12 m/s **
 * b) How far in the horizontal direction has the shot put traveled in .5 s?** d= vi t+ 1/2 at^2 d=8.5 (5) d= 4.25 m

When you launch velocity either increases or decreases. When the initial height is increased or decreased it shows how far the object will travel once it is traveling in the air.
 * 11. Write a script for a sports telecast that describes the motion of a baseball while it is pitched and then hit into the outfield.** The first pitch was just thrown from the pitches hand. It was thrown directly to home plate at a speed of 60 m/s. The batter then hit the ball to center field at an angle of 40 degrees. The ball then dropped into the center fielders glove.
 * What do you think now?**
 * What determines how far an object thrown into the air travels before landing?**

**Most sports have objects or people "flying through the air." Find a relevant video-clip of a sport you might choose for the challenge and describe the following:** http://www.youtube.com/watch?v=inRRaudOf5g **1. how the independence of its horizontal and vertical motions explains its trajectory.** ** The way that the ball is tossed in the air and then hit depends on the path that it is going to take and if it is going to be an accurate serve or not. Depending on how high,low, fast or slow you toss the ball will in the end depend where it is going to land. The higher you move your racket to swing and hit the ball will all depend where the ball is placed and if it reaches the correct box. ** **2. how the shape of the trajectory plays a part in the game.** The shape of the trajectory plays a part in the game because the path that the ball takes all depends if the opponent is going to be able to hit the ball back. If the ball is too far out or too far in, it is going to play a part in if it is a point or not. The way that the ball is hit originally really depends on the end result of where it is located.


 * Physics Plus**

**What do you think now?** **What determines how far an object thrown into the air travels before landing?** When you launch velocity either increases or decreases. When the initial height is increased or decreased it shows how far the object will travel once it is traveling in the air.

=**SECTION 5**=

What do you see?

I see that the girl kicked the ball backwards and it hit another kid in the head it then bounced off the head and it landed into the goal.

** What do you think? ** D**escribe the trajectories of projectiles launched from the ground at various angles.** The smaller angles have long ranges velocities and have a shorter amount of time. Larger angles have smaller velocities and are up for a longer amount of time. The greater the speed the faster the more distance that the object will cover and travel. the range will be longer.
 * Describe how a greater launch speed of a projectile might change the range when the launch angle is the same.**

Physics Talk

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">Summary:
 * Projectiles can have two motions that can act the same.**
 * Constant speed along a straight line, which relates to the launch speed and its direction.**
 * Downward acceleration is caused by gravity which has to do with when the object is launched.**
 * Angle, Speed, Height and range also have to do with projectiles.**
 * The path that the objects make form parabolas.**
 * The Physical model, are evenly spaced strings of calculated lengths**
 * Without air resistance, all trajectories are parabolas.**
 * a 45 degree launch produces the greatest range**
 * small angles have greater horizontal velocities but are for a shorter amount of time**
 * large angles have smaller horizontal velocities but are up for longer amounts of time.**

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">Checking up: <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 1. What are the two types on motion that help you understand the trajectory of a projectile? <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">2. What is the fundamental requirement a scientist must meet when proposing a model of some natural phenomenon? <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">3. For projectiles launched at various angles, summarize how the heigh and range of projectiles vary as the angle of launch is increased from 10 to 80.
 * One motion is constant speed along a straight line, corresponding to the amount of launch speeds, as well as direction. The second one is a downward acceleration, caused by gravity and takes effect upon launch.**.
 * It must must match nature.**
 * When it is increased from 10 to 80 the height increases the range will also increase. At 10 and 80 they have the same range.**


 * Physics Plus**

** Physics to Go ** <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;">**1. If the launching and landing heights for a projectile are equal, what angle produces the greatest range? Why?** <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;">**2. Compared to a launch angle of 45 degrees, what happens to the amount of time a projectile is in the air if the launch angle is** <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;">**a) greater than 45 degrees?** more <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;">**b) less than 45 degrees?** less <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> **3. For a constant launch speed, what angle produces the same range as a launch angle of** <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> **a) 30 degrees? 90-30=60 degrees ** <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> **b) 15 degrees?** 90-15= 75 degrees <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> **4. Analyses of performances of long jumpers has shown that the typical launch angle is about 18 degrees, far less than the angle needed to produce maximum range. Why do you think this occurs**? It is almost impossible to launch yourself at a 45 degree angle. Vix>Viy theta<<<<45 degree <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> **5. You might be familiar with Carl Lewis as a medal winning sprinter. But he is also an olympic gold medalist in the long jump. Why do you think he was successful in both events?** He made sure to jump at a certain angle that he would get maximum distance. He also probably make sure to have a fast initial velocity to allow him to go further. <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;">**6. The diagram below shows a ball thrown toward the east and upward at an angle of 30 degrees to the horizontal. Point x represents the ball's highest point.** <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> **a) What is the direction of the ball's acceleration at point x?** a= -g= -9.8 m/s^2 <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;">**b) What is the direction of the ball's velocity at point x?** Vmax=Vix. this is because vy= 0 at max height
 * 45 degrees because the object will go the furthest. **

**7. A diver jumps horizontally off a cliff with an initial velocity of 5 m/s. The diver strikes the water 3 seconds later.** **a) What is the vertical speed of the diver upon reaching the surface of the water?** <span style="font-family: Arial,Helvetica,sans-serif;">V= Vi +at <span style="font-family: Arial,Helvetica,sans-serif;">(-9.8) (3) = 29.4 m/s <span style="font-family: Arial,Helvetica,sans-serif;"> 29.4 m/s **b) What is the horizontal speed of the diver 1 second after the diver jumps?** 5=Vit vi=5.0 m/s **c) How far from the base of the cliff will the diver strike the water?** d=vit d= 15 m

**8. The diagram of the baseball player shows a baseball being hit with a bat. Angle 0 represents the angle between the horizontal and the ball's initial direction of motion. Which value of 0 would result in the ball traveling the longest horizontal distance if air resistance is neglected?** closest to 45

**9. Four balls, each with mass and initial velocity are thrown at different angles by a baseball player. Neglecting air friction, which angular direction produces the greatest projectile height?** biggest angle

**10. The diagram shows a ball projected horizontally with an initial velocity of 20 m/s east off a cliff 100 m high.** **a) During the flight of the ball, what is the direction of its acceleration?** down **b) How many seconds does the ball take to reach the ground?** -100 = .5(-9.8)t^2 ; t = 4.5 s  **c) How far from the base of the cliff does the ball land?** d=vit+1/2 at^2 d= 20 (4.5)  d= 90 m

45 degrees, gives you the biggest range. Anything that is bigger than 45 gives you more time in the air but the range is smaller. Complementary angles add up to 90 degrees. If two numbers add up to 90 then they have the same range. For example 15 and 75 as well as 40 and 50. It has to be a ground to ground launch. If you launch it faster then it is going to go further.
 * What do you think now?**

=SECTION 6=

I see a person that is on a chair and his feet are on the wall. He pushes off of the wall and goes backward remaining in the chair.
 * What do you see?**


 * What do you think?**
 * If I were to instruct someone on how to jump, I would first tell them to have there feet on the ground. Next thing to do is to bend there knees,and use there feet to push off of the ground. After that, they would be able to jump into the air. The force would be normal going up weight going down. **

<span style="color: #000000; font-family: Arial,helvetica,sans-serif; font-size: 13px; line-height: 19px;">Physics Talk <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 13px; font-weight: normal; line-height: 19px;">Newton's Third Law of Motion:
 * <span style="font-family: Arial,Helvetica,sans-serif;">For every applied force, there is an equal and opposite force. Forces are always equal in the opposite direction. Forces come in equal and opposite pairs. Push on the wall and the wall -pushes back with the same force there is no way to make them unequal.
 * Objects can apply force due to mass and gravity.
 * free body diagram shows the forces acting on an object at a certain time.
 * when standing, your mass is pulling you down. If not for an equal force from the floor that was going up, you would fall down.
 * <span style="font-family: Arial,Helvetica,sans-serif;">for every force applied to object a by another object b, there is an equal and opposite force applied to object b by object a.
 * <span style="font-family: Arial,Helvetica,sans-serif;">if you push or pull on something that something pushes of pulls back on you with an equal amount of force in the opposite direction. this is an inescapable fact- it happens every time

NEWTONS THREE LAWS OF MOTION
 * 1) An object at rest will stay at rest, and an object in motion will stay in motion at constant speed in a straight line unless and unbalanced force acts upon it.
 * 2) Acceleration is directly proportional to net force and inversely proportional to the mass of the system.
 * 3) Every action has an equal and opposite reaction. //all force's come in pairs, but they act on two different systems.//

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">Checking Up Questions 1. Newton's 3rd law of motion states that if you push or pull on something, it will push/pull back with equal force in the opposite direction. Forces come in pairs. 2. Earth pulls down a mass with a force of gravity the mass then pulls up on the Earth with an equal force. 3. A free-body diagram shows the forces acting on an object at a certain time.

1**. When an athlete is preparing to throw a shot put, does the ball exert a force on the athlete's hand equal and opposite to the force the hand exerts on the ball? Explain** ** Yes, that force is what makes it difficult to accelerate. ** **2. When you sit on a chair, the seat of the chair pushes up on your body with a force equal and opposite to your weight. How does the chair "know" exactly how hard to push up on you.** ** There can be springs inside the chair, so that the amount that you compress the chair is equal to your weight. This is a restoring force, so they balance downward. Every single thing compresses it for equal force. ** **3. You have weighed yourself by stepping on a scale many times. How do you think a simple bathroom scale works?** ** Spring with needle attached and it has to balance, and then you get it to equal your weight. The normal force is acting down on the scale and that is giving the same normal force upwards. ** **4. For a hit in baseball, compare the force exerted by the bat on the ball to the force exerted by the ball on the bat. Why do bats sometimes break?** When the force of the bat hits the ball, the person that is holding the bat is adding more force so the ball with travel further. Bats sometimes break because too much force is exerted on them from the force that is present with the bat hits the ball. **5. Compare the amount of force experienced by each football player when a big linebacker tackles a small running b****ack.** When a linebackers tackles a small running back he has more mass and is larger so he is going to knock down the running back when there forces meet. **6. Identify the forces active when a hockey player "hits the boards" at the side of the rink at high speed.** Player hits the boards and its and equal and opposite force that is present. **7. Newton’s second law, F = ma, suggests that when catching a baseball in your hand, a great amount of force is required to stop a high-speed baseball in a very short time interval. The great amount of force is needed to provide the great amount of acceleration required (in this case negative acceleration). Use Newton’s third law to explain why baseball players prefer to wear gloves for catching high-speed baseballs. Use a pair of forces in your explanation.** ** Baseball players prefer to wear gloves when catching a ball because all forces come in pairs so when the ball hits the players glove, his hand is going to need to exert the same force on the ball. When you catch a ball without a glove you move back with it, it allows you to have more distance, which reduces the acceleration and force. ** **8.** **a) Write a sentence or two explaining the physics of an imaginary sports clip using Newton’s third law. How can you make this description more exciting so that it can be used as part of your sports voice-over?**  **b)Describe how deflection of the ground can produce a force. What would make this description more exciting and therefore a valuable part of your sports voice-over?** when a baseball player catches a ball, you can make it more exciting by talking about when the ball hits the persons glove and how it is an equal and opposite force.
 * Physics To Go**

**What do you think now?** When you push on the floor, you are pushing a force on the ground and the floor is pushing a force up on you. When allows for an upward force on you is because you are pushing off of the ground to be able to jump into the air.

=**SECTION 7**= I see a person who is ice skating and they are putting a shoe with an animal inside of it and it is easily gliding. Then the girl is doing the same thing on the beach but it isn't sliding or moving at all, she is needing to exert a lot of force.
 * What do you see?**

Some sports require special shoes because deepening on the surface certain shoes work better. For example if it is frictionless surface you would need different shoes then a surface with friction. Some different features of a shoe that would be useful for different sports are, possibly blades for ice skates, or even certain spikes, to allow for better traction.
 * What do you think?**

<span style="font-family: Helvetica,helvetica,sans-serif; font-size: 12px; line-height: normal;">The force of friction is equal to the force that is read on the spring scale. This is because the pulling force that was applied is equal to the frictional force on the other side. They are in opposite directions so the force to them is zero. it has no units because it is a force divided by a force <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;">the force of friction is= force required to slide the object on the surface with a constant speed.
 * Physics Talk**
 * Friction is a force that resists relative motion between two bodies in contact
 * normal force: the force that is acting perpendicularly or at right angles to the surface
 * coefficient of sliding friction- a dimensionless quantity symbolized by a greek letter u. The value depends on the properties of the two surface in contact.
 * u= force of friction/ perpendicular force exerted by the surface on an object
 * expressed in decimal
 * valid only for the pair of surfaces in contact when the value is measured
 * the force of friction is equal to the force required to slide the object to the surface with constant speed
 * Checking Up Questions**
 * 1. Why can you say that the force of friction is equal to the force reading on the spring scale when pulling an athletic shoe across a surface with a constant speed?**
 * 1. Why can you say that the force of friction is equal to the force reading on the spring scale when pulling an athletic shoe across a surface with a constant speed?**
 * 2. Why doe the coefficient of friction have no units**
 * 3.** **W****hat determines the coefficient of friction?**

<span style="font-family: arial,helvetica,sans-serif; font-size: 14px; font: normal normal normal 12px/normal Helvetica; line-height: 21px; margin: 0px;">** Physics to Go ** <span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;"> **1. Think of a sport and changing weather conditions that would cause an athlete to want to increase friction to have better footing. Name the sport, describe the change in conditions, and explain what the athlete might do to increase friction between the shoes and the surface of the ground.** <span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;"> Track is an example because depending on the weather outside you may need different shoes for better traction. If it icy then the player is going to want to increase the friction of their shoes rather if it is not icy they do not need that much friction on the shoes.

<span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;"> **2. Think of a sport in which athletes desire to have frictional forces as small as possible and describe what the athletes do to reduce friction**. <span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;">In hockey the players want little friction. Because they are on ice they need to slide across the ice quickly to be able to get the puck and score. To reduce the friction of the ice they were ice skates to play.

<span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;"> **3. If a basketball player's shoes provide an amount of friction that is just right when she plays on her home court, can she be sure the same shoes will provide the same amount of friction when playing on another court? What details about the other court would she need to know to answer this question**? <span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;">She can not be sure that the court will provide the same amount of friction. You have to know what the court is made of and see if that is the same material that her shoe is made up of.

<span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;"> **4. Tennis is played on clay, grass, and hard surfaces. Please explain why you think tennis players have or dont have different shoes for each surface?** <span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;">They do have different shoes for each surface. If each court has a different amount of friction then they are going to need to change the pair of shoes for the best results. Its probably much either to slip on some courts then others if you do not change shoes. Hard courts you can actually slide on them and get their a little bit faster.

<span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;"> **5. A cross country skier who weights 600 N has chosen ski wax that provides u = .03. What is the minimum amount of horizontal force, perhaps from a tailwind, that would keep the skier coasting at constant speed across level snow?** <span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;">u=f/N Fy-may N=w=600N .03=f/600 18N=f F-f=0 f=18N

6. **a)** w=mg= (100)(9.8)=9800

µ=f/N 0.55= f/ 9800 5390N=f
 * b)** n-w=0 N=w


 * c**) fx=ma -f=ma -5390=100a -5.39 m/s^2=a

He was not telling the truth because he was traveling at 32.24 m/s actually.
 * e/d)** vf=vi+at 0=vi+(-5.39)(6)= 32.34 m/s

<span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> **7. In some sports, the air or water have limiting effects on motion similar to sliding friction. Do you think that the forces of "air resistance" and "water resistance" remain constant or do they change when speeds change? Use examples from your own experience with these forms of resistance as a basis for your answer.** <span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;"> Air and water do affect motion similar to sliding friction. Air resistance and water resistance remain constant because the speed is changing. When i run outside and getting faster as i go i can feel the wind resistance on my face. Air and water resistance depend on speed.

<span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> **8. If there is a maximum frictional force between your shoe and the track, does that set a limit on how fast you can start (accelerate) in a sprint? Does that mean you cannot have more than a certain acceleration even if you have incredibly strong leg muscles? What is done to solve this problem?** <span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> Yes maximum force limits acceleration. When you are trying to accelerate forward you need the net force forward, and friction is pulling you forward. You need this force. You are only depending on friction to get you going. <span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> **10. Explain why friction is important to running. Why are cleats used in football, soccer, and other sports?** <span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;"> You could not walk if there was no friction. No friction is no walking. Cleats are used for the extra friction because you can have more force on the ground.

<span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> **11. Choose a sport and describe an event in which friction with the ground or the air plays a significant role.** <span style="font-family: arial,helvetica,sans-serif; font-size: 13px; font: normal normal normal 12px/normal Helvetica; line-height: 19px; margin: 0px;"> Today there is a track meet. It was extremely cold last night and there was snow on the ground. The snow turned to ice and now there are very icy conditions for the players. The track runners are going to need to get proper shoes for the icy conditions and are going to need to be even more careful while competing. They need to get shoes that increase the friction to protect their safety.

Physics Plus


 * Lab:Bowling Ball with Blocks**

Table 1 µ || % Difference || class data:
 * Tension (N) || Ff (N) || Total Weight (N) || µ || Class Average
 * **4 3.9 4.1** || **4 N** || **11.8 N** || **.34** || **.325** || **4.6%** ||


 * 0.28 ||
 * .25 ||
 * .25 ||
 * .42 ||
 * .36 ||
 * .34 ||
 * .42 ||
 * .27 ||
 * average: .329 ||

Calculations:

µ = f/N = T/N= 4.8/11.8 =.34 Table 2 (g) || Mass (kg) || Measured Times (s) || Measured Distance (m) || Ff (N) || Acceleration (m/s^2) || Calculated vi (m/s) || Calculated times (s) || % error ||
 * Mass
 * **190.** || **.19** || **1.08** || **2.1** || **.63** || **-3.31** || **3.72** || **1.12** || **3.57%** ||
 * **190** || **.19** || **1.8** || **3.5** || **.63** || **-3.31** || **4.8** || **1.45** || **24%** ||
 * **190** || **.19** || **1.2** || **3.6** || **63** || **-3.31** || **4.9** || **1.36** || **11.76%** ||

=F/N .34=f/ (.19)(9.8)
 * calculations:**

Fy=may .63=.19 (a) =-3.31

vf^2=vi^2+2ad 0= Vi^2+ 2(-3.31)(2.1) 0=vi^2-13.9 3.72=Vi vf^2=vi^2+2ad 0=vi^2 (2) (.3.31) (3.6) 23.8=vi^2 4.9=Vi vf^2=vi^2+2ad 0= Vi^2+2(-3.31)(3.5) =4.8 Vi

Vf=Vi+at vi/a 3.72/-3.31= 1.12 4.8/-3.31=1.45 4.9/-3.31=1.36

(calc time-your time)/calc time X 100

(1.12-1.08)/1.12 X100= 3.57% (1.45-1.8)/1.45 X100= 24% (1.36-1.2)/1.36 X100= 11.76%

1. The coefficient of friction is part one is the friction over the forces going against each other between the block and the ground 2. My mu was .34 and the class was .325 so it was pretty similar a 4.6% difference. The results can change because of random errors or how things were measured, but they should generally be similar. 3. Two of my times were generally close but one was more off then the others. 2 percent errors were low and one was somewhat high which was 24%. 4. It does seem to apply to physics in the real world because in sports these laws apply and you can find the different things that we had to solve for in the lab. Also things constain coefficient of friction in real life like a bowling ball. 5. If the floor was slippery the block would have traveled faster, if the surface was not completely flay and there were bumps it could have changed the acceleration, if when i stopped and started the stopwatch for when my partner threw the block it could have not been exactly correct and the numbers could have varied, and also the way that the distance the block traveled could have not been read exactly with the measuring tape.
 * Questions/ Conclusion**

I think that some sports require different shoes because depending on the surface you may need more or less friction. For almost all sports there are different types of shoes to help you play the best. The coefficient of friction is also used because it is the force of friction over the force required to slide the object on the surface with a constant speed. If you are playing hockey you need The ice skates to help you glide across the surface of the ice because there is a very little amount of friction. Another feature of a shoe that would be useful for a specific sport is cleats. They are used for extra friction for you to stick to the ground. Cleats are used in soccer and football.
 * What do you think now?**

=SECTION 8=

It is a 20 ft high building and they are trying to get into the party. The role allows you to convert your horizontal motion to vertical motion. You cant tell that the people are trying to get speed, so they can then get hight and get to the top where the party is taking place.
 * What do you see?**

I think that they cant vault over a 12- m high bar with a pole that is 11 m long because they do not have enough high and speed to be able to get it that high. The factors that i think limit the the height a pole vaulter can attain, is the speed, the height of the ball and also the distance.
 * What do you think?**

- our technique was to use little ruler as possibly, so the less it hangs off the table the higher that it will go and hit the ceiling. - less the ruler sticks out, greater deflection, position of penny- closer to the end, how flexible the ruler is, how high about the ground the ruler is, mass of the coin.
 * Investigate**
 * a) record your technique for blasting the penny high in the air?**
 * b) what factors about the ruler and how it is positioned determine the height of the penny achieved?**

1. a) we will be able to conclude how different deflections affect the penny. b) we will record the magnitude of the deflection and the height of the penny. c) a ruler for deflection and also for height d) compare the heights to the deflection conclusion: the more the ruler was deflected the further that it would travel.
 * || **trial 1** || **trial 2** || **trial 3** ||
 * **1 cm** || 31 || 29 || 28 ||
 * **2 cm** || 64 || 53 || 60 ||
 * **3 cm** || 82 || 98 || 90 ||

a force can change the position and speed of an object in a way that allows the position and speed to change back Kinetic energy- energy associated with motion gravitational potential energy- energy an object possesses because of its vertical position from Earth potential energy- energy associated with position Law of Conservation of energy: energy cannot be created or destroyed; it can be transformed from one form to another, but the total amount of energy remains constant Energy and Work Work = F x d Elastic Potential Energy = 1/2kx^2 Gravitational Potential Energy = mgh Kinetic energy = 1/2mc^2 Joule = 1 N x m = 1 (kg x m^2 / s^2)
 * Physics Talk**

**k= spring force constant** **Work is caused when a force is exerted over some distance parallel to the motion. W=Fd** __**Law of Conservation of Energy**__ Total energy of system remains constant though the types of energy might change. it //can// be transfered from one type to another The only way to increase or decrease energy is to do work. Initial energy+work done on system= final energy+work done by system
 * **Type of Energy** || **Definition** || **Equation and the Symbo**l ||
 * Kinetic Energy || energy something has because it is moving || KE=1/2 mv^2 ||
 * Elastic Potential Energy || the energy is spring as when it is stretched or compressed || EPE= 1/2 kx^2 ||
 * gravitational potential energy || energy something has due to its location relative to the ground. || GPE= mgh ||
 * Work || is caused when a force is exerted over some distance parallel to the motion || w=Fd ||

Checking up:
 * 1. What is required for the energy of an object to change? A force is the reason for energy to change **
 * 2. From where does the penny that is launched into the air get its energy ? **It gets its energy when you bend the ruler which is elastic potential energy
 * 3. From where does the pole vaulter get the energy needed to bend the pole and then rise over the bar?** The vaulter's kinetic energy is used to give him initial sped upward, and the rest of the kinetic energy is turned into elastic potential energy as the pole bends in.
 * 4. What are the units for work, kinetic energy, gravitational potential energy, and spring potential energy? Joules **


 * Physics To Go**
 * 1.** The shot put is launched by work and is increasing to kinetic energy with is increasing speed. While changing speeds in the air it is kinetic energy. That is then turned into gravitational potential energy as the shot put is thrown above the initial starting point. It then goes back to the ground and stops because of work.


 * 2.** The golf ball stays at rest and then it is hit by the club which is work. The ball then increases and its kinetic energy. When the ball is above the ground it is gravitational energy. On the way back down, there is kinetic energy. It then stops on the ground because of work.

1/2mv^2 = mgh 1/2(12)^2 = (9.8)h 7.3 m = h
 * 3.** KE = GPE


 * 4.** What is limiting the vaulters height is the speed


 * 5.** The pole would increase temperature when the vaulter does work because its kinetic and then elastic energy. But when the pole straightens it will decrease in temperature as the vaulter increases the Gravitational potential energy.

1/2 mv^2= mgh (masses cancel) 1/2 v^2= (9.8) (4.55) v=9.44m/s
 * 6.** KE=GPE

7. KE = GPE 1/2mv^2 = mgh 1/2v^2 = (9.8)6.14 v=10.97 m/s Sergei's speed is higher than Emma's speed.

8a.) GPE = KE mgh = 1/2mv  (9.8)(100) = 1/2v  v = 1960 m/s  8b.) You don't need the mass of the rock because it cancels out

W= 1/2 kx^2 = 1/2 (1500)(0.25)^2 W=46.875 1/2kx^2 = 1/2mv^2 1/2(1500)(.25)^2 =1/2(.1)v^2 v=30.6 m/s
 * 9.** W(pull back)= EPE
 * 9b.)** EPE = KE

1/2kx^2 = F x d 1/2(315)(.3)^2= W 14.2 = W 47.3 N = F
 * 10a.**) EPE = W
 * 10b.)** 14.2 = F x .3

mgh = 1/2kx^2 .04(9.8)(1)=1/2(18)x^2 x = .21
 * 11**) GPE = EPE


 * 12a**. F (measured in N)= m(measured in kg) x a(measured in m/s^2) . so, 1N = 1kg x 1m/s^2
 * 12b**. GPE=mgh ; (kg)(m/s^2) ; 1kg x 1 m/s^2 = J
 * 12****c**. KE=1/2mv^2 ; 1/2(kg)(m/s)^2 ; 1kg x 1 m/s^2 = J
 * 12d.** EPE = 1/2kx^2 ; 1/2[(kg)(m/s^2)/m]m^2 cancels out to 1kg x 1 m/s^2 = J, the same way GPE = kx^2 does
 * 13**. EPE > KE > GPE > KE


 * 14)** During the push up of the ball is work, that work is turned into kinetic, and then to gravitational.


 * 15)** The baseball starts at rest and then it is hit by the bat, which does work on it. It then turns into kinetic energy and the ball is traveling in the air with increasing speed. The kinetic energy then turns into gravitational potential energy, then back to kinetic. Work is then done by the ground so the ball goes back to rest.


 * 16)** In baseball the law of conservation of energy applies. When you or running to the base or even sliding it starts as kinetic energy. As you finally slide into the base it turns into work until you are at rest.

You cannot just double your height if you double the distance because its the speed that matter. The speed of the runner matters because that is what is creating the energy that you get when you throw the pole. The amount of kinetic energy you put in is the same amount of potential energy that you will get out. What limits the height is the speed, their height, also how much the pole stretches. Energy conservation allows for energy that is created while running to stay the same so that the runner is able to get over the pole, and the energy always remains the same.
 * What do you think now?**

=**SECTION 9**=

Someone is ice skating and he is flying in the air and it seems like she is spinning. It seems like she is timing her hang time, because she has a timer with her. There is also a helicopter in the air right near here. I think athletes do follow the laws of gravity. It all depends on the energy and even the force that apply when they are trying to jump. If they spin and jump they are able to have a really long hang time and this follows the laws of gravity.
 * What do you see?**
 * What do you think?**

**Checking Up** 1. The jumper can move from the ready position to the launch position, which is EPE. 2. In launch position the student has both GPE and KE. the top of the jump is GPE 3. Three other types of energy are chemical, light and sound energy.
 * Physics Talk**
 * In ready position, you have EPE from the contractions in the muscles
 * Launch position has GPE and KE
 * energy of all positions of a jumpy are always equal because the conservation energy laws
 * the greater that the peak is, the greater the GPE is

PRE LAB: //For ice skater// 2-3) There were 20 frames (1/30 s) = 2/3 sec 4) At some points the frames were very close in level, because its not that he is not really moving its just that the differences in height are so small it is very hard to see. //For basketball player// 2-3) 31 frames (1/3 s) is about 1 second 4) There was no point when it seemed that he stayed at the same position.
 * Investigate**

1) bend your knees, then unbend knees (still against the floor)then in the air for some amount of time, //Stage A Stage B// W (unbending)=GPE(final)

2) You need to know your weight and the height that we want to achieve

a) We will be able to include how much force we pushed on the ground b) the height we reached and the force we exerted c) the pressure sensor and the meter stick d) seeing if the force is correct to what it should be

Fd=mgh f(.12)= (52)(9.8)(.3) F=1274

5. My calculations were very similar, when i did it on the computer I got 1220, and when I calculated it i got 1274.

My percent error is 4%

W = mgh W = 50(9.8)1 W = 490 J **4**. If they want to prove that the law of physics can be defied, they should prove it with information. After someone should also make sure that that makes sense. You must then show valid evidence that really makes sense to going against the law. The burden of proof is always with the person making the claim. They aren't really proving someone wrong but rather proving something else. **5.** Fd= mgh, you can either increase the force by getting stronger and also increase your mass. **6**. W = F x d **a)** 1N x 1m = 1J  **b)** 1N x 10m = 10J **c)** 10N x 1m = 10J **d)** .1N x 100m = 10J **e)** 100N x .1m = 10J
 * Physics To Go**
 * 1**. W = GPE
 * 2.** Work is converted into KE. The KE and GPE are converted into more KE when they reach the bottom of the hill. W=KE=KE+GPE=KE=W. As your KE goes up your GPE is going down.
 * 3**. If we want to see if the statement is correct we would need to see were the payers foot is during each frame, during a specific amount of time. From here you can see that the player does not actually hang in the air, but his max height has been displaced.

**7**. W = GPE **a)** 1N x 1m = 1J **b)** 1N x 10m = 10J **c)** 10N x 1m = 10J **d)** .1N x 100m = 10J **e)** 100N x .1m = 10J

**8**. KE = GPE **a)** 1N x 1m = 1J **b)** 1N x 10m = 10J **c)** 10N x 1m = 10J **d)** .1N x 100m = 10J **e)** 100N x .1m = 10J

50 x 43 2150 J
 * 9.** W = F x d

=1/2(62)8.2^2 KE=2084 J
 * 10)**KE=1/2(m)v^2

=30/5 =6m/s^2
 * 11a**)a=f/m

=30(18.75) =563 J
 * 11b)**W=fd

40000=3200d d=12.5m
 * 12a)** w=fd

3200/12.5 =2.7 m/s^2
 * 12b)**f/m=a

1/2(m)v^2=W 1/2(.15)40^2=w 120 J = W
 * 13)** KE=W

fd=1/2(m)v^2 417d=1/2(64)15^2 d=17 M
 * 14)** W=KE

**15)** pole || 10 ||  || 90 || 100 ||
 * || KE || GPE || EPE || Sum ||
 * running || 100 || 0 || 0 || 100 ||
 * full bend of the
 * peak height || 0 || 100 || 0 || 100 ||
 * landing || 75 || 25 || 0 || 100 ||
 * cushion collaspe || 0 || 0 || 0 || 100 ||


 * 16)**
 * || KE || GPE || EPE || SUM ||
 * peak height || 0 || 1000 || 0 || 1000J ||
 * landing || 800 || 200 || 0 || 1000J ||
 * lowest height || 0 || 0 || 1000 || 1000 J ||


 * 17)**
 * || KE || GPE || EPE || SUM ||
 * top of the mountain || 0 || 1000 || 0 || 1000 ||
 * middle || 500 || 500 || 0 || 1000 ||
 * bottom || 1000 || 0 || 0 || 1000 ||
 * 18)** In baseball when the batter swings and hits the ball with the bat there is work present. Then work then changes into Kinetic Energy because the speed is increasing. When the ball is moving in the air it is GPE. Then when the ball slows down and reaches the ground in the end it turns back into work.


 * Physics Plus**

mgh=1/2mv^2 (9.8)(20)=1/2 mv^2 196=1/2 mv^2 392=v^2 19.8=v
 * 1a)** GPE=KE
 * 1b)** The mass of the car does not matter because they cancel out on both sides, because objects in free fall fall at the same rate regardless of mass. You need the roller coaster to work no matter what the weight of the people in the carts are.

1/2 kx^2+mgh=1/2mv^2 v=4.2
 * 2.** EPE+GPE=KE

200(9.8)h=1/2(200) h=20 m
 * 3.** GPE=KE

Athletes do not defy gravity. This is because the figure skater is always moving while they are in the air, even if it is very small and hard to see, they are still moving. Its just that the movement is very slight so it is hard to see. All of the energy that the figure skater got from the work as well as the kinetic energy allows them to push themself into the air because the law of conservation of energy is still there.
 * What do you think now?**

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