Among iron and copper electrons move freely in which of them?

A1,200 kg car is accelerated at 3.7 m/s2. what force was needed to produce this acceleration? a. 4,440 n b. 324.3 n c. 4,388 n d. 304.3 n

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.)

An object moves from the position +34m to the position -15m in 15 seconds. what is it's total displacement? what is it's average velocity?