Table 3: Momentum and Kinetic Energy before and after a collision
Mass of Red Cart (kg) Mass of Blue Cart (kg) Cart vo (m/s) vf (m/s) Po (kg m/s) Pf (kg m/s) KEo (kg m^2/s^2) KEf (kg m^2/s^2)
Red
Blue
P(sys)o =
P(sys)f =
KE(sys)o =
KE(sys)f =
Show the calculations here for P(sys)o, P(sys)f, KE(sys)o, and KE(sys)f.
P(sys)f =
KE(sys)o =
KE(sys)f =
3. Using your data, explain how you know that momentum was conserved, but kinetic energy was not conserved.
Collision with stationary cart
4. You should have found that the pair of carts moving as one with a mass of 2 * mcart had half the speed of the single cart with a mass of 1 * mcart. Why then is the kinetic energy less after the collision? That is, why doesn't one cart with a speed of v have the same kinetic energy as two carts each with a speed of v^2?
Here's a head start to your answer. Before the collision, the object carrying all the momentum and KE had a mass of mcart and a speed of vo. For the situation in Graph III1, what fraction of the kinetic energy of the carts remains after the collision? That is, what is (KEfinal/KEinitial)? You don't have any numbers to work with, but you don't need any. For the situation in Graph III2, what fraction of the kinetic energy of the carts remains after the collision? That is, compute (KEfinal/KEinitial). You'll need to use your numbers this time. Show calculations of total KEfinal/KEinitial here.