Just one question please help :)

only answer if you actually know please!

Thanks sooo much!!

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.)

Why is the energy that results from a roller coaster's position at the top of a hill referred to as potential energy?

What is similar between metals and suspensions