Two cars come to a stop from the same initial speed, one braking gently and the other braking hard. Which car converts more kinetic energy to internal energy (for example, thermal energy in the brakes)

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.)

Can anybody me with this? ? (picture included.)

Choose all the answers that apply. our solar system: is in a spiral galaxy no longer includes pluto is made mostly of empty space is in the andromeda galaxy is the only known system that supports life