Chapter+3

= =

= = =toc SECTION 1=

There is a picture of a car that is in a car crash, the front of the car is all smashed in, the driver went forward and into the air bag, a teddy bear is flying in the air, that must of came from the back seat of the car with the child. You can see that the driver had to push the breaks, because of the lines and air behind the car.
 * What do you see?**

I can protect myself from a serious injury by always wearing my seatbelt. Also making sure that there are air bags can greatly protect my if i were to get into an accident.
 * What do you think?**

**Investigate** 2. assistant analysis (12 points), I was surprised with my knowledge, because I didn't know that I knew as much as I actually did.

(yes/no) || New Cars (1,2,3) ||
 * ** Safety features ** || Means of protection || Pre-1960 cars
 * **seat belts** || keeps driver and passengers inside of car || n || 1,all ||
 * **head restraints** || prevents whiplash || n || 1,all ||
 * **front airbags** || cushions during collisions || n || 1, all (drivers side ||
 * **back up sensing system** || allows to see in blind spots, while backing up || n || 3, few ||
 * **front crumple zones** || increase collisions distance reducing impact || n || 1,2 all, some ||
 * **rear crumple zones** || increase collisions distance reducing impact || n || 2, some ||
 * **side-impact beams in doors** || resists side penetration || n || 2, some ||
 * **shoulder belts for all seats** || keeps passengers in seats during collisions || n || 1,all ||
 * **anti-lock braking systems (ABS)** || helps maintain control/ prevents skids || n || 2, some ||
 * **tempered shatterproof glass** || helps prevent cuts || y || 1, all ||
 * **side airbags** || protects head/ torso in side of collisions || n || 2,some ||
 * **turn signals** || warns other drivers of actions || y || 1, all ||
 * **electronic stability control** || helps resist rollovers || n || 2, 3, some, few ||
 * **energy-absorbing collapsible steering column** || prevents chest trauma || n || 1, all ||


 * Physics Talk**
 * If you are in an accident, in a safer vehicle, the chances of injury will be limited
 * People in the car are not the only ones that are in danger
 * The book Unsafe at Any Speed, showed the problems with no seat belts, having hard chrome dashboards, and solid steering column.
 * Since this point vehicle safety has been improved
 * Four wheel drive fatal accidents, increased by 85% and then decreased by 25%.
 * The increase in fatal 4WD crashed could be due to the growing number of lm traveled by the 4WD.
 * It could also be due to the tendency of some drivers to increase speed under the impression that the safety features will protect them


 * Checking Up Questions**
 * 1.** They ways that cars are now safer is that they have seat belts, don't have hard chrome dashboards, and solid steering columns.
 * 2.** When drivers travel a greater distance they feel that four wheel drive will protect them, so they have an tendency to increase there speed.

1. Side air bags (S,T) turn signals (R,F,S,T), side- impact beams (S), rear crumple zones (R), front crumple zones (F),seat belts, (F,R), head restraints (R,F), front airbags (F,R,T), shoulder belts (F,R,S,T), shatterproof glass (F,R,S,) breaks (F,R,S,T) 2. Bike Safety Features/ knee pads, elbow pads, helmet, reflector, wrist pads 3. In-Line Skating Safety Features/ helmet, knee pads, elbow pads, wrist pads 4. Skate Boarding Safety Features/ helmet, knee pads, elbow pads, wrist pads
 * Physics To Go**

You can protect yourself from injury by making sure the car you are driving is equipped wit things like airbags, seat belts, four wheel drive and turing signals. If you aren't in a car but rather, a bike or skating, having proper helmets and padding can ensure your safety as well. Its important to check your car and make sure that you have the proper things working just in case something were to happen to you. What actions will not protect you in an accident is not wearing your seatbelt
 * What do you think now?**

=SECTION 2=

 Investigate X2: Newton's FIrst Law and Seatbelts


 * Objectives:**


 * What happens to a passenger involved in a car accident without and with a seatbelt?
 * What factors affect the passenger’s safety after a collision?
 * How would a seat belt for a race car be different from one available on a regular car?


 * Hypothesis:** Respond to each of the above objectives fully.


 * If a passenger is wearing a seatbelt while in a car accident it will hold them in place and prevent them from moving from their seat. If a passenger is not wearing their seatbelt they can be thrown from their seat and possible be ejected from the car. The things that affect the passengers safety after a collision are if you were strapped into the car or not. A seat belt would be different for a race car then a different car because for a race car it would need to be much stronger and hold the passenger in place even better because they are traveling at much faster speeds then a regular car would.**

Materials: **List any materials used and draw a labeled diagram of your set-up (alternatively, include a snapshot or video).** cart, clay, ramp with end stop, wire, thread, string, yarn, ribbon, rubber bands, textbooks, tissue box
 * The height of the ramp is .365 m and this is the height where the figure got injured.**


 * Procedure:**
 * 1) Make a clay figure and then place the figure in the cart.
 * 2) Arrange a ramp so that the endstop is at the bottom of the ramp.
 * 3) Adjust the height of the ramp to make a very shallow incline.
 * 4) Send the cart down the ramp.
 * 5) Very gradually increase the height of the ramp until significant “injury” happens to your figure. Make a note of this height.
 * 6) Fix your clay figure. Create a seatbelt for the figure and take a "Before" picture and post in your data table.
 * 7) Send your cart and passenger down the ramp at the same height as in Step 5. Be sure to record your observations specifically and carefully. Take an "After" picture and post in your data table to supplement your written observations.
 * 8) Repeat Steps 6 and 7, using different types of material for the seatbelt.

Data and observations: Injury Height with no seatbelt: _ m

through his body and sliced his neck. || 6 ||
 * **//Type of Seatbelt//** || //**Before Picture**// || //**After Picture**// || //**Description and Observations**// || //**Group**// ||
 * Thread || [[image:proringer:theadmadread.jpg height="192" caption="theadmadread.jpg"]] || [[image:proringer:thread_madread_2.jpg height="192" caption="thread_madread_2.jpg"]] || Arm chopped off. The seat belt cut
 * Wire || [[image:proringer:hershey_kissboybefore.jpg height="192" caption="hershey_kissboybefore.jpg"]] || [[image:proringer:hersheykissafter.jpg height="189" caption="hersheykissafter.jpg"]] || The wire was wrapped around him pretty tightly. The passenger was severely injured because the wire sliced through his arms and chest. It is clearly the thin dense material that did this || 1 ||
 * Yarn || [[image:proringer:bj_string_one.jpg height="192" caption="bj_string_one.jpg"]] || [[image:proringer:bj_string_twozel.jpg height="192" caption="bj_string_twozel.jpg"]] || Our observation of the string seat belt is that when the accident occurred, the figure slammed forward. This shows that the string is not sturdy enough to prevent an injury in an accident || 5 ||
 * String || [[image:proringer:stringlapoop.jpg height="192" caption="stringlapoop.jpg"]] || [[image:proringer:stringlapoop2.jpg height="192" caption="stringlapoop2.jpg"]] || Our seatbelt made of string went around the chest. After going down the ramp, our passenger was still in the cart without any injuries. || 2 ||
 * Ribbon || [[image:proringer:panso_x3_ribbon.jpg height="192" caption="panso_x3_ribbon.jpg"]] || [[image:proringer:panso_ribbon_x4.jpg height="192" caption="panso_ribbon_x4.jpg"]] || We made a seatbelt out of ribbon that went around his waist shoulders and chest. When the cart went down the ramp, the seatbelt held him in place and the clay person didn't leave the cart. || 3 ||
 * tape || [[image:proringer:mitchel_lalalal_masking.jpg height="192" caption="mitchel_lalalal_masking.jpg"]] || [[image:proringer:michell_lalal_2_masking.jpg height="192" caption="michell_lalal_2_masking.jpg"]] || we took a piece of tape and folded it over so there was no sticky part. We then twirled the end to make tying it easier. We put the tape belt around "her" waist and tied it around the bottom of the cart. Despite my face in the after picture, the tape actually worked well because our figure was unharmed and barely moved. ||  ||

//** *Read the Physics Talk p268 - 271 before answering the following questions. * **// 1. Define the terms: inertia, force and pressure. Pressure is force per area where the force is normal [perpendicular] to the surface, measured in N/m^2 or Pa;
 * Questions:**
 * Inertia is the natural tendency for an object to remain at rest or to remain moving with a constant speed in a straight line.**
 * Force is an interaction with two objects that results in acceleration.**

2. In the collision, the car stops abruptly. What happens to the “passenger”?
 * The passenger is launched forward towards the front of the car.**

3. What parts of your passenger were in greatest danger (most damaged)?
 * The inside of the body are most in danger. Your heart is still moving at the same rate as the car as well as the brain, they never stop moving. There needs to be an unbalanced force to stop it, and your body wall is the force that stops the organs from moving around.**

4. What does Newton’s first law have to do with this?
 * Because your insides are still moving inside your body there must be an unbalanced force to stop it. Your body wall is that force that stops this.**

5. What materials were most effective as seatbelts? Why?
 * Materials that are most effective are things that are thick and will really hold back the person like ribbon or tape. If something like a wire is used it is very thin and can cut into the passengers body.**

6. Use Newton's first law of motion to describe the three collisions. **First collision: the automobile strikes the pole, the pole exerts the force that brings the automobile to rest. Because the object will not stop moving until something hits it.** **Second collision: when the automobile stops, the body keeps moving. The structure of the automobile exerts the force that brings the body to rest** **Third collision: The body stops, but the heart, the brain and other organs keep moving. The body wall exerts the force that brings the organs to res**t.

7. Why does a broad band of material work better as a seatbelt than a narrow wire?
 * All the force is spread out over a much larger area.**

Conclusion: Using Newton's First law of Motion, explain why a seat belt is an important safety feature in a vehicle. What factors affect the effectiveness of a seatbelt? What would you need to consider when designing a seatbelt for a race car? Use specific observations from this investigation to support your answers to these questions.
 * A seatbelt is really an important safety feature that must be in all cars because of newtons first law of motion. It keeps your body moving until another force is acting on it. The seatbelt serves as that force to stop the body from continuing to move forward. If you were to make a seatbelt for a race car you would probably want a thick material. Because the car is going to be moving so fast you need a larger force to stop the drivers body from moving forward. The bigger material the more the force will be spread out from effecting the body. In the investigation we used wire and since this was so thin it cut right into the body of the person and can really cause damage.**

Explain at least 1 cause of experimental error. Be sure you describe a specific reason.
 * One error would be the way that we tied our wire around the passenger. We tied it pretty tight to begin with and it easily went into the person because he was made of clay. Maybe we should have wrapped the wire around differently and it wouldn't have cut into the person as much.**

How would you improve the results of this lab? (In other words, what would you change about the materials or procedure to eliminate or reduce the experimental error you describe above?)
 * If I were to change something that we did it would be to tie the wire around the person more effectively. I also feel that maybe everyone should have used the same height for their ramp to really see how each of the materials effected the person. Maybe the person should not have been made of clay so we could realistically see what the material would do to the body.**

USE THE RUBRIC TO MAKE SURE YOU HAVE INCLUDED ALL REQUIREMENTS!

= Section 3 = Investigate X3: Energy and Air Bags

**Objective:**** How does an air bag protect you during an accident? **
 * Hypothesis:** Respond to the objective fully.**An airbag is safer because our bodies are moving in a straight constant motion until we are acting on by a unbalanced force. The air bad stops you from moving forward.**

**Materials:** List any materials used and draw a labeled diagram of your set-up (alternatively, include a snapshot or video).**egg, flour, plastic bag, ruler, balance, bowl with rice, scale**

**Procedure:**

**Note: //You may want to use the available technology to take "Before" and "After" pics to post in your data table to assist and elaborate on your written descriptions.//**

1. Measure the height of your egg #1. =**.053 m** 2. Place an egg in a ziplock bag, squeezing out all of the air in the bag before sealing. 3. Hold a ruler up on the table vertically. Hold the egg vertically at the 2 cm mark. (Keep the excess bag on top.) Drop it. Record your observations. 4. Hold the egg the same exact way at the 4-cm mark and repeat. Continue this process until the egg shell is slightly cracked. 5. Continue until the egg is smashed and the yolk leaks out. Measure the amount of egg still undamaged. How much of the egg is smashed? Be sure to record detailed observations. 6. Fill a bowl with rice and place the bowl inside of the box lid. 7. Measure the height of your egg #2. **.056 m** 8. Drop the egg from the smash height (Step 3) **14 cm**. Measure the amount of egg sticking up out of the rice bed. How much of the egg is buried in the rice? Also, record your observations. 9. Repeat this, increasing the height in 2-cm increments until the egg is cracked, and then smashed.

//**Data and observations:** Add more columns/row as needed.//


 * **Egg #** || **Drop Height** || **Cracked or Smashed?** || **Description and Observations** || Before || After ||
 * 1 || 2 cm || stayed the same || At 2 cm the egg did not even crack because it didn't even move || [[image:giordanowikilog:Photo_66.jpg height="144" caption="Photo_66.jpg"]] || [[image:giordanowikilog:Photo_66.jpg height="144" caption="Photo_66.jpg"]] ||
 * 1 || 4 cm || Got a small crack at the bottom || At 4 cm the egg slightly cracked at the bottom. || [[image:giordanowikilog:Photo_66.jpg height="144" caption="Photo_66.jpg"]] || [[image:giordanowikilog:Photo_67.jpg height="144" caption="Photo_67.jpg"]] ||
 * 1 || 6 cm || cracked a little more || At 6 cm the egg cracked more and there is an even bigger dent || [[image:giordanowikilog:Photo_67.jpg height="144" caption="Photo_67.jpg"]] || [[image:giordanowikilog:Photo_68.jpg height="144" caption="Photo_68.jpg"]] ||
 * 1 || 8 cm || cracked more || At 8 cm the crack got even larger then before || [[image:giordanowikilog:Photo_68.jpg height="144" caption="Photo_68.jpg"]] || [[image:giordanowikilog:Photo_68.jpg height="144" caption="Photo_68.jpg"]] ||
 * 1 || 10 cm || cracked || At 10 cm some of the yolk is starting to come out of the egg slowly || [[image:giordanowikilog:Photo_68.jpg height="144" caption="Photo_68.jpg"]] || [[image:giordanowikilog:Photo_69.jpg height="144" caption="Photo_69.jpg"]] ||
 * 1 || 12 cm || really cracked || At 12 cm there is a huge crack on the side || [[image:giordanowikilog:Photo_69.jpg height="144" caption="Photo_69.jpg"]] || [[image:giordanowikilog:Photo_70.jpg height="144" caption="Photo_70.jpg"]] ||
 * 1 || 14 cm || smashed || at 14 cm the egg completely smashed || [[image:giordanowikilog:Photo_70.jpg height="144" caption="Photo_70.jpg"]] || [[image:giordanowikilog:Photo_71.jpg height="144" caption="Photo_71.jpg"]] ||
 * 2 || 14 cm || nothing happened || nothing happened to the egg and it is sticking out .037 meters and is buried in .019 meters of flower || [[image:giordanowikilog:Photo_66.jpg height="144" caption="Photo_66.jpg"]] || [[image:giordanowikilog:Photo_72.jpg width="192" height="144" caption="Photo_72.jpg"]] ||
 * 2 || 18 cm || nothing happened || it did not crack and it is sticking out .029 meters and it is buried in .011 || [[image:giordanowikilog:Photo_72.jpg height="144" caption="Photo_72.jpg"]] || [[image:giordanowikilog:Photo_72.jpg height="144" caption="Photo_72.jpg"]] ||
 * 2 || 22 cm || nothing happened || It did not crack and it is sticking out || [[image:giordanowikilog:Photo_72.jpg height="144" caption="Photo_72.jpg"]] || [[image:giordanowikilog:Photo_72.jpg height="144" caption="Photo_72.jpg"]] ||
 * 2 || 28 cm || nothing || with added flour it is sticking out .022 meters and buried in .018 meters still without a crack. || [[image:giordanowikilog:Photo_72.jpg height="144" caption="Photo_72.jpg"]] || [[image:giordanowikilog:Photo_73.jpg width="192" height="144" caption="Photo_73.jpg"]] ||
 * 2 || 36 cm || nothing || it is sticking out .018 meters and buried in .022 meters still without a crack. || [[image:giordanowikilog:Photo_73.jpg height="144" caption="Photo_73.jpg"]] || [[image:giordanowikilog:Photo_73.jpg height="144" caption="Photo_73.jpg"]] ||
 * 2 || 45 cm || nothing || it is sticking out .021 meters and buried in .019 meters still without a crack. || [[image:giordanowikilog:Photo_73.jpg height="144" caption="Photo_73.jpg"]] || [[image:giordanowikilog:Photo_73.jpg height="144" caption="Photo_73.jpg"]] ||
 * 2 || 60 cm || nothing || it is sticking out .019 meters and buried in .021 meters still without a crack. || [[image:giordanowikilog:Photo_73.jpg height="144" caption="Photo_73.jpg"]] || [[image:giordanowikilog:Photo_73.jpg height="144" caption="Photo_73.jpg"]] ||
 * 2 || 90 cm || nothing || it is sticking out .017 meters and buried in .023 meters still without a crack. || [[image:giordanowikilog:Photo_73.jpg height="144" caption="Photo_73.jpg"]] || [[image:giordanowikilog:Photo_73.jpg height="144" caption="Photo_73.jpg"]] ||
 * 2 || from celling to floor || cracked || from the ceiling the egg completely cracked and was sticking out .01 meters and buried .03 meters || [[image:giordanowikilog:Photo_73.jpg height="144" caption="Photo_73.jpg"]] || [[image:giordanowikilog:Photo_74.jpg width="192" height="144" caption="Photo_74.jpg"]] ||

**Calculations:** Show equation(s), numbers plugged in, and answer with correct units. Add columns in your data table to include these results. What is the gravitational potential energy in each trial?
 * How much work is done in each trial?
 * How much force was used to stop the egg in each case of steps 5, 8 and 9.

** *Read the Physics Talk p279 - 287 before answering the following questions. * **

Questions:

The egg is representing the person that is moving at a constant straight motion in a collision. The table represents the windshield of the car which is the surface in front of it. The flour is the airbag that acts as the unbalanced force.
 * This investigate is an analogy for a person in an automobile collision. What does the egg represent? What does the table represent? What does the rice represent?**

kinetic energy is the energy that is caused by a moving body and work is the amount of force applied on an object over a certain amount of distance.
 * Define the terms: Kinetic Energy and Work.**

the mass and the velocity of the object
 * What factors determine an objects kinetic energy**

Work can increase the kinetic energy or decrease it because it depends on which way the force is and the displacement in which the object is moving.
 * When work is done on an object, what is the effect on the object's kinetic energy.**

The object stopping the object must do work and the greater the distance the less the force that there is.
 * How does the force needed to stop a moving object depend on the distance the force acts on it.**

If it is a soft landing area in a collision, it decreases the kinetic energy of the person, because it slows them down. The energy of the landing increases, it acts as the airbag on the person.
 * What difference does a soft landing area make on a passenger during a collision?**

Cushions are able to protect the person in the car because it increases the distance it takes to stop in the accident. It also stops your body from hitting the front of the car. An object in motion remains in motion unless acted upon by an unbalanced force, so the object in motion is the person that is in the car and the unbalanced force is the airbag that stops and protects the person.
 * How does the cushion reduce the force needed to stop a passenger?**
 * What does the law of conservation of energy have to do with this?**


 * Conclusion:**
 * Using the law of conservation of energy, explain how an air bag can protect you during an accident. Use specific observations from this investigation to support your answers to these questions.
 * <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">**Because of the law of conservation of energy, a person in a crash remains in motion at constant speed unless something acts upon them like a dashboard or an airbag. The hard surface would have to do work to stop the person. To decrease a large force the airbags must increase the distance.** **In order to decrease the large force, airbags are used as cushions to increase the distance. In our lab the flour was used an airbag and the egg was the person. The more flour the more distance and the less force.**
 * <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">Explain at least 1 cause of experimental error. Be sure you describe a specific reason.
 * <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">**An error would be that the height we dropped the egg may not be exact so our math could be a little off depending on the exact distance. Also the flour changed the shape that it was in, in the bowl so it could be different for every trail that we ran. The distance the egg was exposed could have changed because of this.**
 * <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">How would you improve the results of this lab? (In other words, what would you change about the materials or procedure to eliminate or reduce the experimental error you describe above?)
 * <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">**I would improve the results by changing the flour, and make it more exact. Each time i would run a trial I would make sure that it was exactly even in the bowl to make sure I was getting accurate numbers.**

=**Notes on Section 5**=
 * momentum- quantity of motion described by the product mass and velocity. p=mv
 * to get a lot of momentum: large mass and small velocity //or// a small mass and a large velocity or large mass and a large velocity


 * Physics To Go**

p=mv =1000 (10) = 10,000 (kg) (m/s)
 * 1. Suppose an automobile collides with another automobile that is stopped. If both automobiles have the same mass, what do you expect to happen in resulting collision?** The automobile that collides into the other car will have a greater momentum because its velocity is greater than a car that is not moving.
 * 4. Why do football teams prefer offensive and defensive linemen who weight about 140 kg (about 300 lb)?** They want the linemen to have a greater mass than the other players so when they are tacking and hitting into each other the linemen will have more momentum than the player on the other team.
 * 5. What determines who will get knocked backward when a big vehicle collides with a smaller vehicle in a head-on collision?** The smaller vehicle with the smaller mass will get knocked backwards in a head on collision, because it is lighter than the bigger vehicle.
 * 6. A 1000 kg automobile is moving at 10.0 m/s. At what speed would a 10,000-kg truck need to travel in the same direction so that the momentum of the two would be equal?**

=section 6= <span style="font-size: 1.3em; margin: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 5px;">** Investigate X6: Momentum and Inelastic Collisions **


 * Objective: What physics principles do the traffic-accident investigators use to "reconstruct" the accident?**


 * Materials: List any materials used and draw a labeled diagram of your set-up (alternatively, include a snapshot or video).**
 * Two carts, track, motion detector, masses **


 * Procedure: **


 * 1) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">Place a motion detector at the right end of a track. Open up data studio. Dump "Velocity" into "Graph" display, and enlarge this.
 * 2) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">Place a cart on the middle of the track with the velcro to the right. Call this the "target cart." Place a second identical cart on the right end of the track. Call this the "Bullet cart".
 * 3) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">Click "Start" on Data Studio, and then push the bullet cart very gently towards the target cart so that they collide and stick together. You may need to practice this a few times. Be sure to get your body out of the way of the motion detector!
 * 4) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">Examine the graph produced by the motion detector. Using the Smart Tool, find the velocity right before and right after the collision. Record this in your data table.
 * 5) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">Vary the masses of the carts and repeat the process 5 times.

//**Data and observations:** Add more columns/row as needed.//
 * **Mass of Bullet Cart (kg)** || **Mass of Target Cart (kg)** || **Speed of Bullet Cart**(m/s) || **Speed of Target cart (m/s)** || **Combined masses (kg)** || **Final Velocity of both carts (m/s)** || Initial Momentum Bullet Cart m/s(kg) || Final Momentum Both carts m/s(kg) || Initial Momentum Target Cart || Sum Initial Momentum Both ||
 * .498 || .501 || .62 || 0 || .999 || .28 || .31 || .28 || 0 || .31 ||
 * .498 || .9993 || .47 || 0 || 1.4973 || .14 || .23 || .21 || 0 || .23 ||
 * .9963 || .501 || .43 || 0 || 1.4973 || .14 || .43 || .21 || 0 || .43 ||
 * .995 || .9993 || .47 || 0 || 1.9943 || .18 || .47 || .36 || 0 || .47 ||
 * .995 || 1.2493 || .55 || 0 || 2.2443 || .23 || .55 || .52 || 0 || .55 ||
 * Calculations:** Show equation(s), numbers plugged in, and answer with correct units. Add columns in your data table to include these results.

1. Find the initial momentum of the bullet cart for each trial. P=mv P = (.498 kg)(.62 m/s) P = .31 m/s(kg)

2. Find the initial momentum of the target cart for each trial. P=mv P=(.501kg)(0m/s) P = 0 kg(m/s)

3. Find the sum of the initial momenta of the two carts for each trial. initial momentum of Bullet Cart

4.Find the final momentum of the combined carts for each trial. P = mv P = (.999kg)(.28m/s) P = .28 kg(m/s)

** *Read the Physics Talk p312 - 315 before answering the following questions. * **
 * Questions:**
 * 1) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">Compare the initial momenta (calc 3) to the final momentum (calc 4). (Allow for minor variations due to uncertainties of measurement.)
 * **For almost all of the trials, except for the third one the final and initial momentums were the same.**
 * 1) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">List the 6 types of collisions (top of page 312) and a brief description.
 * **1) A moving object hits a stationary object and they stuck together and move forward at the same speed**
 * **2) Two stationary objects explode by the release of a spring between them and move off and opposite directions**
 * **3) One moving object hits a stationary object and the first object stops and the second moves forward.**
 * **4) one moving object hits a stationary object and they both move off in different speeds**
 * **5) two moving objects collide and they both move at different speeds after the collision**
 * **6) two moving objects stick together and move off at the same speed**
 * 1) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">Which types of collisions are definitely inelastic? How do you know?
 * **It is one when the objects do not bounce off of each other, but rather stay and move together like types one and six.**
 * 1) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">Which types of collisions are definitely elastic? How do you know?
 * **It is when objects bounce off of each other like types two,four and five.**
 * 1) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">Define the law of conservation of momentum.
 * **The total momentum before a collision is equal to the total momentum after the collision if no external forces act on the system.**
 * 1) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0.5em; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">Use the law of conservation of momentum to describe what happens when a cue ball hits the 15 balls in the middle of the pool table.
 * **The total momentum of the balls after the collision equals the momentum of the cue ball. The objects can move in new directions but the momentum always remains the same.**


 * Conclusion:**


 * 1. Based on the law of conservation of momentum, how can the traffic-accident investigators use to "reconstruct" the accident? What does it mean to "conserve" momentum? **
 * **The investigators must know the masses and velocities of the vehicles because from here they can find the momentum, before the collision. From here they would be able to find out the same from after the collision. To conserve momentum the vehicles have the same momentum before and after a collision.**


 * 2. Explain at least 1 cause of expermential error. Be sure you use specific reasons. **
 * **One cause of experimental error would be the way the track was on the table. It was on a slight incline so the carts would move even when they were flat. This would change the velocity slightly which is a main factor is calculating the momentum.**


 * 3. How would you improve the results of this lab? **
 * **I would improve the results by making sure that the track was flat on the table so the carts would only move when something acted upon them.**


 * Physics To Go**

**2a**. p=mv <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px; padding: 0px;"> Cart A: =(1)(2) = 2 kg (m/s) <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px; padding: 0px;"> Cart B = (1)(-2) = -2 kg (m/s) <span style="font-family: arial,helvetica,sans-serif;">**2c.** Final momentum <span style="font-family: arial,helvetica,sans-serif;">mvi + m2vi2 = mvf + m2vf2 <span style="font-family: arial,helvetica,sans-serif;"> (1kg)(2m/s) + (1kg)(-2m/s) = (1kg)(vf) + (1kg)(Vf2) <span style="font-family: arial,helvetica,sans-serif;"> 0 = 2kg(vf) <span style="font-family: arial,helvetica,sans-serif;">the final momentum is 0.
 * 2.** [cart 1]--> <--- [cart 2]

<span style="font-family: arial,helvetica,sans-serif;">**3.** mvi + m2vi2 = mvf + m2vf2 m (vi) =m4+m4 mvi=8m vi=8 m/s


 * 5.** The change in momentum is zero because of the law of conservation of momentum.

(2000)(3)+ (2000)(2)=4000 vf 6000+4000= 4000vf 10,000=4000vf vf=2.5 m/s
 * 6.**mvi + m2vi2 = mvf + m2vf2

80 (10)+100 (8)=80 vif+100 (9.78) 800+800=80 vif+978 1600= 80v9f+978 622=80vif 7.8 m/s=vif
 * 7.** mvi + m2vi2 = mvf + m2vf2

(3) (2)+ 1(-2)= 3(0)= 1v2f 6-2=v2f 4m/s= v2f
 * 8.**mvi + m2vi2 = mvf + m2vf2

=**Section 7**=

Physics To go <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">4. Explain why you bend your knees when you jump to the ground.
 * You must bend your knees when you jump to the ground because it minimizes the force. You knees act as a crumble zone so that your legs don't break when you hit the ground from the force that is exerted.**

**<span style="font-family: arial,helvetica,sans-serif; font-weight: normal; font: normal normal normal 13px/normal Arial; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;">6. An automobile has a mass of 1200 kg and an initial velocity of 10m/s. Calculate the change in momentum required to do the following: ** a) Bring to rest **p= (1200) (0-10)**  **= -12000 kg m/s** b) Slow to 5 m/s
 * p=(1200) (5-10)**
 * = -60000 kg m/s**

<span style="font-family: arial,helvetica,sans-serif; font-weight: normal; font: normal normal normal 13px/normal Arial; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"> 7. If the braking force for an automobile is 10,000 N, calculate the impulse if the brake is applied for 1.2 s. If the automobile has a mass of 1200 kg what is the change in velocity of the automobile over this 1.2 s time interval? <span style="font-family: arial,helvetica,sans-serif; font-weight: normal; font: normal normal normal 13px/normal Arial; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"> **Ft=m(^)v** <span style="font-family: arial,helvetica,sans-serif; font-weight: normal; font: normal normal normal 13px/normal Arial; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"> **10,000(1.2)= 1200Ns** **12,000=1200v** **10 m/s = (change) velocity**

<span style="font-family: arial,helvetica,sans-serif; font-weight: normal; font: normal normal normal 13px/normal Arial; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"> 8. A 1500 kg automobile traveling at 5 m/s after braking strikes a power pole and comes to a full stop in 1 s. Calculate the force exerted by the power pole and brakes required to stop the automobile. <span style="font-family: arial,helvetica,sans-serif; font-weight: normal; font: normal normal normal 13px/normal Arial; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"> **Ft=m(^)v** <span style="font-family: arial,helvetica,sans-serif; font-weight: normal; font: normal normal normal 13px/normal Arial; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"> **F(1)=1500(-5)** <span style="font-family: arial,helvetica,sans-serif; font-weight: normal; font: normal normal normal 13px/normal Arial; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"> **F= 7,500 N**

<span style="font-family: arial,helvetica,sans-serif; font-weight: normal; font: normal normal normal 13px/normal Arial; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;">10. **The one with the bigger area is a more dangerous collision because the one that has a higher maximum force with a shorter time is going to be more dangerous.**