Ch+3+Sec+6+KirnumB

** 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).

2 carts motion detector track

Procedure:
 * 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.

//**Data and observations:** Add more columns/row as needed.//
 * **Mass of Bullet Cart (kg)** || **Mass of Target Cart (kg)** || **Speed of Bullet Ca****rt (m/s)** || **Speed of Target cart (m/s)** || **Combined masses (kg)** || **Final Velocity of both carts (m/s)** || momentum of bullet cart || moentum of the target cart || Sum of initial momentum of the two carts (kgm/s^2) || Final momentum of the combined carts **_** ||
 * .499 || .501 || .85 || 0 || 1 || .33 || .42415 || 0 || .33 || .33 ||
 * .999 || .501 || .56 || 0 || 1.5 || .36 || .55944 || 0 || .36 || .54 ||
 * .499 || 1.001 || .71 || 0 || 1.5 || .25 || .35429 || 0 || .25 || .38 ||
 * .499 || 1.251 || .80 || 0 || 1.75 || .29 || .3992 || 0 || .29 || .51 ||
 * 1.249 || .501 || .56 || 0 || 1.75 || .35 || .69944 || 0 || .35 || .61 ||
 * .999 || 1.001 || .67 || 0 || 2 || .3 || .66933 || 0 || .3 || .60 ||
 * .749 || .751 || .85 || 0 || 1.5 || .46 || .63665 || 0 || .46 || .69 ||


 * 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=(.499)(.85)
 * P=.424
 * 1) Find the initial momentum of the target cart for each trial.
 * P=mv
 * P=(.751)(0)
 * P=0
 * 1) Find the sum of the initial momenta of the two carts for each trial.
 * 0+.33=.33
 * 1) Find the final momentum of the combined carts for each trial.
 * Pf=mv
 * Pf=1(.33)=.33

***Read the Physics Talk p312 - 315 before answering the following questions.** *
 * Questions:**
 * 1) Compare the initial momenta (calc 3) to the final momentum (calc 4). (Allow for minor variations due to uncertainties of measurement.)
 * They are very similar for most of the calculations
 * 1) List the 6 types of collisions (top of page 312) and a brief description.
 * A moving object hits a stationary object: both stick together and move at the same speed
 * Two stationary objects explode by the release of a spring: they move off in opposite directions
 * One moving object his a stationary object: Second object moves off
 * One moving object hits a stationary object: both move off at different speeds
 * Two moving objects collide: both move apart at different speeds
 * Two moving objects collide and stick together: move off at the same speed
 * 1) Which types of collisions are definitely inelastic? How do you know?
 * The ones that separate after the collision, if they were elastic, they would stick together
 * 1) Which types of collisions are definitely elastic? How do you know?
 * The ones that stick together ^
 * 1) Define the law of conservation of momentum.
 * The total momentum before a collision is equal to the total momentum after the collision if there is no external forces acting on the system
 * 1) 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 momentum from the cue ball gets transferred into the other balls, causing them to break apart.

· 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? · 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?)
 * Conclusion:**
 * Traffic accident investigators can conserve momentum by lessening the speed limit. By doing this, they are making cars take more time and conserving momentum.
 * One error would be using the wrong side of the cart
 * To improve this lab, I would make sure that each ramp is level to make sure the results are correct.