posted by David .
A railroad car (m=3000 kg) is coasting along a level track with an initial speed of 22 m/s. A load of coal is then dropped into the car as sketched in the figure below.
(a) What are the velocities of the car and the coal before the collision along the x direction?
(b) If the final speed of the car plus coal is 17 m/s, what is the mass of the coal?