A1400 kg car moving +13.7 m/s makes an elastic collision with a 3200 kg truck, initially at rest. what is the velocity of the car after the collision?
(unit = m/s)

Agroup of students were investigating the force of gravity. they began by dropping a foam ball from a height of 3 meters into a bucket of sand. the ball hit the sand in 0.306 seconds. they dropped additional balls of approximately the same diameter, but of different masses. here is the data they collected. based on this experiment and the collected data, what would their conclusion be?