After the pendulum is dropped, determine the height at which the kinetic energy is equal to the potential energy.

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.)

To do work, this truck uses energy stored in chemical fuel and an electrical battery. how much total energy does this truck put out?

What is the weight of a feather (mass = 0.0001 kg) that floats through earth's and the moon's atmospheres?