Physics 231: General Physics I Lab 7 Mar. 25, 2004 Names: Collisions Goals: 1. to understand the definition of momentum, esecially that it is a ector. 2. To exerimentally erify conseration of momentum for one-dimensional collisions. 3. To get ractice determining whether or not collisions are elastic. Part one: One-Dimensional Collisions You will erform two different one-dimensional collisions between carts. In one collision the carts should stick together and be of different masses, and in the other they should bounce off of each other and be of like masses (this makes the mathematical rediction much easier). You will note that one end of each cart contains magnets. With the magnetic ends of two carts facing each other, the carts will bounce. If the carts do not actually collide, you will get less energy dissiation to sound and heat, and thus hae an elastic collision. Plug two motion detectors into Lab Pro (one in Sonic 1 and the other in Sonic 2). Oen Collisions (in Physics Exeriments/ 220 221 / Collisions). You will hae one motion detector at each end of the track, if aimed roerly (and set to their narrow range) each detector should only track the cart nearest to it. Play around a little with your set-u to make sure you e got the motion detectors roerly aimed to only sense one car each. Note: Friction will drain momentum from the carts. To minimize friction s effect on your data, use elocity measurements from immediately before and after the collisions. Collision #1: stick together, different masses You ll begin with one cart sitting still and the other moing toward it. 1. Record the masses of the carts. m 1 m 2 2. Record the initial and final elocities of the carts including the signs (on the Analyze menu, select Examine). 1o 2o 1f 2f 3. Pre-Lab: Sketch the initial and final situations. Be sure to label the carts and indicate the directions of their elocities.
4. Pre-Lab: Deelo an equation for the final seed of the carts, ( f ) deending only on m 1, m 2, 1i, and 2i. 5. Plug your measurements for the initial conditions into this equation. 1f 6. How does the redicted elocity comare with that measured? (Calculate the ercentage f calc difference.) 100% 7. How does the initial total kinetic energy comare with the final total kinetic energy? (Calculate the ercentage change.) 100% 8. How does the initial total momentum comare with the final total momentum? (Calculate r r i measured the ercentage change.) r 100% 9. Was momentum consered in the collision? Exlain. 10. Was the collision elastic? Exlain.
Collision #2: carts bounce aart, same mass You will again start with one cart stationary. 11. Record the masses of the carts. m 1 m 2 12. Record the initial and final elocities of the carts including the signs (on the Analyze menu, select Examine). 1o 2o 1f 2f 13. Pre-Lab: Sketch the initial and final situations. Be sure to label the carts and indicate the directions of their elocities. 14. Pre-Lab: Assuming a comletely elastic collision ( K. 0), deelo an equation for the final seed of one of the carts, ( 1f ) deending only on 1i, and 2i (not on 2f.) note: it would deend on the masses, but they ll cancel out if they re equal to eachother. 15. Plug your measurements into this equation. 1f 16. How does the redicted elocity comare with that measured? (Calculate the ercentage f calc difference.) 100%
17. How does the initial total kinetic energy comare with the final total kinetic energy? (Calculate the ercentage change.) 100% 18. How does the initial total momentum comare with the final total momentum? (Calculate r r i measured the ercentage change.) r 100% 19. Was momentum consered in the collision? Exlain. 20. Was the collision elastic? Exlain.
Lab #6: Pre-lab Name: 3. Pre-Lab: Sketch the initial and final situations. Be sure to label the carts and indicate the directions of their elocities. 4. Pre-Lab: Deelo an equation for the final seed of the carts, ( f ) deending only on m 1, m 2, 1i, and 2i. 13. Pre-Lab: Sketch the initial and final situations. Be sure to label the carts and indicate the directions of their elocities. 14. Pre-Lab: Assuming a comletely elastic collision ( K. 0), deelo an equation for the final seed of one of the carts, ( 1f ) deending only on 1i, and 2i (not on 2f.) note: it would deend on the masses, but they ll cancel out if they re equal to eachother.