D. When Alan's puck is moving at 21 m/s south, it collides with an ice skate of mass 2 kg sitting on the rink. Alan's
puck bounces backward at a speed of 4 m/s. What is the
momentum of the puck-skate system before the collision?

Ten students stand in a circle and are told to make a transverse wave. what best describes the motion of the students? each student bumps the shoulder of his or her neighbor. at the exact time, all students take a step to the right. the students skip clockwise, going in a circular motion. one at a time, each student lifts his or her hands up and then down.

It is really hard for me right know

Agraduated cylinder contains 63.0 ml of water. a piece of gold, which has a density of 19.3 g/ cm3, is added to the water and the volume goes up to 64.5 ml. calculate the mass in grams of the gold that was added to the water. explain how you got your answer.