- When an object is dropped what happens to potential and kinetic energy as it falls? A. GPE goes up KE goes down
C. GPE goes down, KE goes down
B. GPE goes up. KE goes up
D. GPE goes down, KE does up

Aboxcar traveling at 12 m/s approaches a string of 5 identical boxcars sitting stationary on the track. the moving boxcar collides and links with the stationary cars and they all move off together along the track. what is the final speed of the cars immediately after the collision? (you may take the mass of each boxcar to be 18,537 kg.)

Rohit is trying to tune an instrument

Amoving electron has kinetic energy k1. after a net amount of work w has been done on it, the electron is moving one-quarter as fast in the opposite direction. (a) find w in terms of k1. (b) does your answer depend on the final direction of the electron's motion?