Chapter+3

=Chapter 3= Car Crash: [] in this article a mini van crashed into a road barrier in the bronx. The passenger and the driver were both killed.

INVESTIGATE 1What do you see? There is a car crash test and the car is absorbing the impact and collapsing in the front. the driver is going forward and into an airbag. the teddy bear did not have a seat belt on and went flying.

What do you think? How can you protect yourself if serious injury does occur? A car crashing into Wearing a seat belt can prevent serious injuries that could happen if you were to get into an accident.

Investigate: Step 2: I earned 11 points which makes me an assistant analysis. I thought that I knew more than I did.

(yes/no) || New Cars (1,2,3) || Physics talk: Car safety wasnt always a priority until about 1960. An activist wrote a book explaining the dangers of not have airbags, seat belts and other necessary safety devices. We have noticed the decrease of accidents now that it is mandatory to have certain devices like solid steering columns, hard chrome dashboards, and seat belts. Some are priced separately, but those who dont invest, end up in a accident. Checking up questions: 1. Three ways that manufatures made cars safer are they added mandatory seat belts, shoulder belts, air bags and solid steering columns. 2. What are who explanations why there is an increase of accidents in 4WD crashes.People might feel too comfortable, people speed thinking that the safety features will keep them completely safe. physics to go 1.side impact beams- side, shoulder belts, all of them, anti lock breaks- all, side air bags- sides, crumple zones (rear) - rear, (front)- front. Side and rear view mirrors- all, helps you see all around you. The padding helps prevent head injuries. 2,helmet, knee pads, elbow pads, and wrist pads 3.helmets, knee pads, elbow pads and wrist pads 4.helmets, knee pads, elbow pads and wrist pads. 5. What do you think now? You can protect yourself by driving a modern car with all new safety devices. The actions that wont protect you from an accident would be wearing a helmet in the car. Also bracing yourself would not help either. Your reaction time is too small.
 * ** Safety features ** || Means of protection || Pre-1960 cars
 * seat belts || If there is a collision it keeps the person in the seat rather than flying out of the car. || no || 1 all ||
 * head restraints || Keeps your head from snapping backwards in a collision ( head rest) prevents whip lash || no || 1 all ||
 * front airbags || Keeps you from flying forward. keeps you from hitting your head on the wheel || no || 1 all drivers side ||
 * back up sensing system || Shows you what is behind you when reversing the car. || no || 3, few ||
 * front crumple zones || that increases the time when an accident occurs || no || all or some ||
 * rear crumple zones || increases distance || no || 2 some ||
 * side-impact beams in doors || stiffening bars, renforce the car || no || some ||
 * shoulder belts for all seats || Stops your upper body from flying forward || no || 1 ||
 * anti-lock braking systems (ABS) || prevents skids || no || 2 ||
 * tempered shatterproof glass || prevents broken glass || yes || all ||
 * side airbags || prevents injury || no || some ||
 * turn signals || tells other cars your direction of route || yes || all ||
 * electronic stability control || helps resists rollovers || no` || some to few ||
 * energy-absorbing collapsible steering column || prevents chest trama || yes || all ||

X3 Investigate:
 * Objectives:**
 * What happens to a passenger involved in a car accident without and with a seatbelt? If they are not wearing a seatbelt and they crash they can be projected forward.
 * 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: If a passenger is not wearing a seatbelt in a time of a crash they could be projected forward. A seat belt in a race car has to be different then a regular one because it has to be stronger to hold the person in his or her seat when moving at fast speeds.**

Observations: two books the person is fine- no impact. three books: still little impact. four books: there is more impact on the person five books the person hits head and mangles arm and leg


 * **//Type of Seatbelt//** || //**Before Picture**// || //**After Picture**// || //**Description and Observations**// || //**Group**// ||
 * Thread || [[image:jdthread.jpg width="256" height="192"]] || [[image:jdpthread2.jpg width="256" height="192"]] || Arm chopped off. The seat belt cut through his body and sliced his neck. || 6 ||
 * .Wire || [[image:wire1jdp.jpg width="256" height="192"]] || [[image:wire2jdp.jpg width="256" height="192"]] || The wire was put around the passenger pretty tightly in order for him to stay on the cart after the collision. The wire was so tight that it sliced his arms and chest. The wire material is not a good idea because it can harm the person even if the collision wasnt that bad. || 1 ||
 * String || [[image:string1jdp.jpg width="256" height="192"]] || [[image:string2jdp.jpg width="256" height="192"]] || 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 ||
 * Yarn || [[image:yarnjdp.jpg width="256" height="192"]] || [[image:yarn2jdp.jpg width="256" height="192"]] || Our observation of the yarn seatbelt is that when the accident occurred, the figure slammed forward. This shows that the yarn is not sturdy enough to prevent an injury in an accident. || 5 ||
 * Ribbon || [[image:ribbonjdp.jpg width="256" height="192"]] || [[image:ribbon2jdp.jpg width="256" height="192"]] || 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 didnt move. ||  ||
 * TAPE || [[image:tape1jdp.jpg width="256" height="192"]] || [[image:tape2jdp.jpg width="256" height="192"]] || The tape was able to hold the person in the car at the greatest height and acceleration || 4 ||

//** *Read the Physics Talk p268 - 271 before answering the following questions. * **// Questions:
 * 1) Define the terms: inertia, force and pressure.Inertia is an objects existing state or constant motion. Does not change unless an outside force acts on it. Force: something that acts upon a steady object producing motion. Pressure: a continuous physical force exerted against an object.
 * 2) In the collision, the car stops abruptly. What happens to the “passenger”?The passenger will jolt forward.
 * 3) What parts of your passenger were in greatest danger (most damaged)?His head and arms were the most damaged.
 * 4) What does Newton’s first law have to do with this?The person was going in the proper path until an outside force was exerted. (the collison)
 * 5) What materials were most effective as seatbelts? Why?The tape was very effective as when we sent out person down the ramp, our seatbelt was able to keep our person in the car regardless of the force acting on it.
 * 6) Use Newton's first law of motion to describe the three collisions.
 * 7) Why does a broad band of material work better as a seatbelt than a narrow wire?

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. · Explain at least 1 cause of experimental error. Be sure you describe a specific reason. · 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?)

height: .035m || || the egg is completely smashed and the yolk is no longer in the shell ||
 * **Egg #** || **Mass** || **Before Picture** || **Drop Height** || **Indent** || **Cracked or Smashed?** || **After Picture** || **Description and Observations** ||
 * 1: .05m || .05743 kg || [[image:brookerphysicslog:begggyy4.jpg width="351" height="265" caption="begggyy4.jpg"]] || .02m ||  || nothing ||   || no crack ||
 * 1: .05m || .05743 kg ||  || .04m ||   || cracked ||   || crack has begun ||
 * 1: .05m || .05743 kg ||  || .06m ||   || more cracked ||   || larger crack ||
 * 1: .05m || .05743 kg ||  || .08m ||   || cracked ||   || even larger crack ||
 * 1: .05m || .05743 kg ||  || .1m ||   || cracked ||   || crack growing ||
 * 1: .05m || .05743 kg ||  || .12m ||   || cracked ||   || crack growing ||
 * 1: .05m || .05743 kg ||  || .14m ||   || cracked ||   || crack growing ||
 * 1: .05m || .05743 kg ||  || .16m ||   || leaking ||   || the egg is leaking ||
 * 1: .05m || .05743 kg ||  || .18m ||   || leaking ||   || the egg is leaking ||
 * 1: .05m || .05743 kg ||  || .2m ||   || leaking ||   || the egg is leaking ||
 * 1: .05m || .05743 kg ||  || .22m ||   || leaking ||   || the egg is leaking ||
 * 1: .05m || .05743 kg ||  || .24m ||   || leaking ||   || the egg is leaking ||
 * 1: .035m || .05743 kg ||  || .26m ||   || smashed
 * 2: .05m || .05436kg ||  || .26m || .03m || nothing happened ||   ||   ||
 * ||  ||   || .3m || .03 || nothing happened ||   ||   ||
 * ||  ||   || .34 || .028 || nothing happened ||   ||   ||
 * ||  ||   || .4 || .027 || nothing ||   ||   ||
 * ||  ||   || .46 || .026 || nothing ||   ||   ||
 * ||  ||   || .52 || .025 || nothing ||   ||   ||
 * ||  ||   || .58 || .22 || nothing ||   ||   ||
 * ||  ||   || .64 || .2 || nothing ||   ||   ||
 * ||  ||   || ceiling ||   || nothing ||   ||   ||


 * 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. * ** 1. 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? The egg represents the person in the car accident. When the egg breaks it represents the person getting hurt. The table represents the object that the car is crashing into and the rice or flour represents the airbag protecting the person 2. Define the terms: Kinetic Energy and Work. Kinetic energy is the energy the object has when it is moving. It is determined by the objects mass and velocity. Work is the amount of force applied on an object over a certain distance. 3. What factors determine an object's kinetic energy? Velocity and mass determine the kinetic energy. When work is done on an object, what is the effect on the object's kinetic energy? It can either decrease or increase the objects kinetic energy depending on the direction of the object and the distance the object moves. 4. How does the force needed to stop a moving object depend on the distance the force acts? The work needed to stop an automobile is fixed depending on its velocity because it must match the kinetic energy, so if the distance is larger the force is most likely smaller and if the distance is smaller the force is probably larger. 5. What difference does a soft landing area make on a passenger during a collision? A soft area landing makes a passenger safer during a collision because it protects their body and head with cushion. 6. How does a cushion reduce the force needed to stop a passenger? When a cushion like an airbag strikes a person, they traveler a larger stopping distance and therefore, less force is needed to stop them. 7. What does the law of conservation of energy have to do with this? This applies to the conservation of energy because the law states that energy can not be created or destroyed, and this deals with how kinetic energy is turned into work when a person or automobile in a crash stops moving. The person for example is moving which is kinetic energy but the airbag is the force that holds them back. These two types of energy are always going to be equal according to the law of conservation of energy.
 * Questions:**

1.) 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. The airbag is used to protect a person in a collision. It is supposed to hold the person back because when there is a collision, they will continue to move forward until a force (the airbag) acts on him. The law of conservation of energy says that the kinetic energy can't be destroyed, it must be transferred into the form of work. The force of work is the airbag.
 * Conclusion:**

2.) Explain at least 1 cause of experimental error. Be sure you describe a specific reason. One experimental error in this lab could have been if we dropped the egg at the wrong distance. If we dropped it from a couple centimeters up, our calculations would be wrong.

3.) 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?) To improve this lab I would probably have tested dropping the egg from the same distance several times to see if i measured the indentation in the flour right. I would probably also use a smaller ruler rather than a meter stick to measure the indent in the flour because it might be easier to read.

Section 5:

Investigate 5
Objective: A small sports car hits a heaby truck in a collision. What factors determine the outcome for the passengers of the two vehicles? Which driver will sustain worse injuries? Why? The factors that determine the outcome are mass, acceleration, force and momentum. The sports car driver will have worse injuries because the truck has a lot more mass than the sports car. Materials: List any materials used and draw a labeled diagram of your set-up (alternatively, include a snapshot or video). - carts - mass - ramp - mystery cart

Procedure:


 * 1) Place a cart on the middle of the track with the spring 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".
 * 2) Push the bullet cart very gently towards the target cart so that they collide, with the spring between them.
 * 3) Repeat step 2 several times, giving the bullet cart a bigger push each time. Record your observations.
 * 4) Add 500-g to each cart and repeat the process. Record your observations and compare the results to the first set of collisions.
 * 5) Remove the mass from the target cart and repeat the above steps.
 * 6) Add the mass to the target cart and remove the mass from the bullet cart, and repeat.
 * 7) Get the "Mystery" cart from your teacher. Determine the relative mass of the cart by putting it through a sequence of collisions.

- We thought that the Mystery cart "A" was lighter than the 500 gram one so it could be like 450 grams. //**Data and observations:** Add more columns/row as needed.//
 * **Bullet Cart** || **Target Cart** || **Applied force** || **Description and Observations** ||  ||
 * normal || normal ||  || The harder we pushed the bullet cart, the farther the target cart went. ||   ||
 * +500 || +500 ||  || The same thing happened but the cart did not go as far. ||   ||
 * normal || +500 ||  || the car went further than it did in the normal experiment. ||   ||
 * +500 || normal ||  || The cart did not go as far as normal. ||   ||


 * Questions:**
 * 1) What is a real-life collision that the collisions in this investigation could represent?
 * 2) The real life collision would be a car crashing into the back of another car.
 * 3) How well did observing collisions enable you to compare the masses of the carts in the last step?
 * 4) It helped us make an assumption on the mass because we knew what masses we were adding, and could compare it to the actions that resulted in the mystery cart A. Depending on which direction the carts moved in we could determine which had a heavier or lighter mass depending on the speed.
 * 5) What happened after the collision as the masses changed?
 * 6) The cart with the lighter mass was moved further by the one with the heavier mass
 * 7) Define the term momentum. Momentum is the engergy that carries over from a mass and a velocity.
 * 8) The product of the mass and velocity of an object, it is a vector quantity and is given the symbol p
 * 9) Which object has greater momentum, a butterfly traveling at 16 km/h or an eagle traveling at the same speed? An eagle because it has more mass
 * 10) The eagle has greater momentum because it has a bigger mass and they are going the same velocity. If you use the formula for momentum (p=mv) you can determine that the eagle has more momentum
 * 11) How does the transfer of momentum occur?
 * 12) Momentum transfers in situations like a parked car being hit by a moving one, the moving car slows down and hte parked one moves away from it at the same speed. The moving car transfers momentum to the second one
 * 13) Use momentum to describe what would happen if a skaterboarder was hit by a car.
 * 14) If a skateboarder was hit by a moving car the boarder would be pushed away with a higher speed than the car. Because of its large mass it would hig hte boarder hard and transfer a lot of momentum to the skateboarder, moving him far and fast. The car looses its momentum when the boarder gains it. This would probably result in an injury to the boarder.

· Based on the relative amounts of momentum, what is the outcome of a head-on collision between a heavy truck and a small sports car if both have the same speed? The sports car would be pushed further because it has less mass than the truck which is much larger. · Explain at least 1 cause of experimental error. Be sure you describe a specific reason. If we didn't use the same force each time we tried it, it would cause our observations to vary. · 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?) We could improve this lab by using something else that would push the cart with the same force each time, ensuring that our results would be more accurate.
 * Conclusion:**

Discussion Questions
Physics to go: 1 . It depends on the speed of the moving car. They switch momentum. The velocity of car that stikes the parked car will be transferred to the parked car. 4. The bigger the player, the more momentum they will have, making it harder for others to knock them down. 5. The mass and velocity of each car. The vehicle with the bigger momentum it will crush the other. 6. p=mv 1000=m 10=v p=10,000. for both cars to have equal momentum the 10,000 kg truck would have to move at 1 m/s.

Investigate X6: Momentum and Inelastic Collisions
Objective: See the force the different mass has on either cart.

Materials: track, two carts, two 500 masses

Procedure: where it hits: 1. .71 .44
 * 1) Place a motion detector at the right end of a track. Open up data studio. Dump "Velocity" into "Graph" display, and enlarge this.
 * 2) 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) 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) 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) Vary the masses of the carts and repeat the process 5 times.

2. .54 .40

//**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) || initial momentum (target cart) || final momentum of the combined carts. || sum of the initial momenta of the two carts. ||
 * .257 || .257 || .71 || 0 || .71 || .44 || .18247 || 0 || .3124 || .18247 ||
 * .757 || .257 || .54 || 0 || .54 || .40 || .40878 || 0 || .216 || .40878 ||
 * .757 || .757 || .5 || 0 || .5 || .2 || .3785 || 0 || .1 || .3785 ||
 * .257 || .757 || .41 || 0 || .41 || .3 || .10537 || 0 || .123 || .10537 ||


 * Calculations:** Show equation(s), numbers plugged in, and answer with correct units. Add columns in your data table to include these results.

Find the initial momentum of the bullet cart for each trial p=mv p=.257(.71) p=.18247 p=mv p=(.257)(0) p=0 same as bullet cart. p=mv p=.71(.44) .3124
 * 1) Find the initial momentum of the target cart for each trial.
 * 1) Find the sum of the initial momenta of the two carts for each trial.
 * 1) Find the final momentum of the combined carts for each trial.

** *Read the Physics Talk p312 - 315 before answering the following questions. * **


 * 1) Compare the initial momenta (calc 3) to the final momentum (calc 4). (Allow for minor variations due to uncertainties of measurement.)
 * 2) **Except for the third trial, in all of the tests, the initial and final momentum were practically the same.**
 * 3) List the 6 types of collisions (top of page 312) and a brief description.
 * 4) **One moving object hits a stationary object and both stick together and move off at the same speed.**
 * 5) **Two stationary objects explode by the release of a spring between them and move off in opp. directions**
 * 6) **one moving object hits a stationary object. the first object stops, and the second object moves off**
 * 7) **one moving object hits a stationary object, and both move off at different speeds.**
 * 8) **two moving objects collide, and both objects move at different speeds after the collision**
 * 9) **two moving objects stick together and move off at the same speed**
 * 10) Which types of collisions are definitely inelastic? How do you know?
 * 11) **an inelastic collision is one where objects do not bounce off if each other, but rather move off together. Types 1 and 6 are inelastic.**
 * 12) Which types of collisions are definitely elastic? How do you know?
 * 13) **an elastic collision is one where objects bounce off of each other. Types 2, 4, and 5 are definitely elastic.**
 * 14) Define the law of conservation of momentum.
 * 15) **the total momentum before a collision is equal to the total momentum after the collision if no external forces act on the system.**
 * 16) 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.
 * 17) **the sum of the momentum of all the balls right after the collision is equal to the momentum of the original cue ball. This is because nature conserves momentum.** **The objects may move in new directions and with new speeds, but the momentum stays the same.**


 * Conclusion:**
 * 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
 * **If the investigators know the masses and velocities (momentum) of the vehicles before the collision, they can accurately display the masses and velocities (momentum) after the collision.**
 * **conserve means to maintain. By conserving momentum, the vehicles have the same momentum before & after a collision.**
 * Explain at least 1 cause of experimental error. Be sure you describe a specific reason.
 * **the flat track that the carts were being pushed around on was on a slight incline due to uneven materials on the bottom of the track. This could have offset the velocity, which is a key factor in calculating momentum.**
 * 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?)
 * **I would improve the results of this lab by using a track the was fully flat to the table with no incline. That way, the target cart would stay still on its own and the velocities would be more accurate**

ptg

PTG 2. X--> <--X <--XX-->

2a. p=mv Cart A: =(1)(2) = 2 kg (m/s)  Cart B = (1)(-2) = -2 kg (m/s)

2b. momentum before mvi + m2vi2 = P before (1kg)(2m/s) + (1kg)(-2m/s) 0 = Pbefore 2c. momentum after mvi + m2vi2 = mvf + m2vf2 (1kg)(2m/s) + (1kg)(-2m/s) = (1kg)(vf) + (1kg)(Vf2) 0 = 2kg(vf) 0 = Vf..... finally velocity of both carts is zero total momentum after the collision = 0.

3. mvi + m2vi2 = mvf + m2vf2 mVi + 0 = m(4) + m(4) mVi = 8m vi= 8 m/s

5. After they collide, vehicle B gains momentum (the 4000 kg(m/s) that vehicle A lost. The change in momentum of the system is zero because although A loses momentum, it is transferred to B.

6. mvi + m2vi2 = mvf + m2vf (2000kg)(3m/s) + (2000kg)(2m/s) = 2000Vf + 2000Vf 10000 = 4000 Vf 2.5 m/s = Vf

7. mvi + m2vi2 = mvf + m2vf2 80kg(10m/s) + (100kg)(8m/s) = 80kg(Vf) + (100kg)(9.78m/s) 622 = 80Vf 7.8 m/s = Vf

8. mvi + m2vi2 = mvf + m2vf2 (3)(2) + (1)(-2) = (3)(0) + (1)(Vf) 4 m/s = Vf2

**Investigate 7: Impulse and the Crumple Zone**
// Objective: A crumple zone is part of the body of a car that compresses during an impact. It absorbs the energy of the collision and lessens the force on the passengers. //
 * What are some of the factors that car designers and engineers must consider when designing a crumple zone as a safety feature? Engineers must consider the force acting on the car when a collision takes place.
 * What enables a passenger to survive a collision? All the safety features built into the car such as air bags, head restraints and seat belts help you survive accidents.
 * What does a Force vs. Time graph look like for a collision? Its going to be a curved graph because there will be a lot of force in a small amount of time. Starts out small and then reaches a maximum and then comes back down.
 * What would the Force vs. Time graph look like if the collision was more safe?The curve will not be as steep and will be slightly wider. The force will be spread out in a greater amount of time.

// Materials: List any materials used and draw a labeled diagram of your set-up (alternatively, include a snapshot or video). //

//Procedure:// // 1. On the floor, place a ramp on a stand so that one end is raised 10-cm and the other end is 20 cm from the wall. // // 2. Place a block in the cart and attach a 2-cm piece of masking tape to the front of the block and down onto the cart. Place the cart at the top of the ramp and release it. Record your observations. // // 3. Design a crumple zone to protect the block from tipping over. You can use only the following materials: one sheet of paper, 30-cm tape, 2 rubber bands, and 30-cm of string. Record your design(s) and the changes you make to it in a data table. You may want to use the available technology (still pictures and video) to supplement your written descriptions. // // 4. Measure the mass of your cart with apparatus attached. // // 5. Once you have a functional design that you are happy with, you will bring it to the front of the room to test. You will allow your cart to crash into a force sensor in order to generate a force vs. time graph, while a motion detector will measure the speed of the cart. // // 6. Click the ∑ button to get the area of the F-t Graph. Click the smart tool to get the velocity of the cart before and after the collision. // // 7. Repeat 3 times. //


 * Data and observations:** Add more columns/row as needed.
 * **Trial** || **Mass of Cart with apparatus(kg)** || **Speed of Cart** before collision(m/s) || **Speed of cart after collision (m/s)** || **Area on F-t graph (Ns)** || **Change in momentum (kgm/s)** || **Impulse (Ns)** ||
 * No Crumple Zone (teacher) ||  ||   ||   ||   ||   ||   ||
 * #1 with CZ ||  ||   ||   ||   ||   ||   ||
 * #2 with CZ ||  ||   ||   ||   ||   ||   ||
 * #3 with CZ ||  ||   ||   ||   ||   ||   ||

**Calculations:** Show equation(s), numbers plugged in, and answer with correct units. Add columns in your data table to include these results. 1. Calculate the change in momentum for your cart. 2. Impulse is equal to the area of the F-t graph. What is the impulse experienced by your cart?

***Read the Physics Talk p324 - 329 before answering the following questions.** *

1. Define the following terms: velocity, acceleration, Newton’s second law of motion, and momentum, impulse. 2. What is a crumple zone? 3. Why is it safer to collide with a soft cushion than a hard surface? 4. What is the relationship between impulse and change in momentum? 5. How is the impulse-momentum relationship related to Newton’s second law? 6. What were the key features of your crumple zone and why were they important? 7. What happened to the area of the Force-time graph as we increased the speed of the cart? 8. What happened to the area of the Force-time graph when the collision was inelastic vs. elastic?
 * Questions:**

**Conclusion:** · What are some of the factors that car designers and engineers must consider when designing a crumple zone as a safety feature? Compare and contrast crumple zones and air bags. · Explain at least 1 cause of experimental error. Be sure you describe a specific reason. · 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?)