Momentum of 0.5 kg moving ball with the velocity of 5 m / s

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.)

What will a positive and a negative charge do if they are separated from each other?

Looking at this barometer, is the air pressure high or low? what type of weather would you expect? high, bad low, bad high, good low, good