What is the tension on the rope

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.)

Waves that cause the most damage during an earthquake are a. surface waves c. s waves b. p waves d. ocean waves

Which situation will produce the greatest change of momentum