Question

Why does the force of gravity do no work on a hockey puck sliding across the ice into the goal?

Answer 1

The force of gravity does no work on a hockey puck sliding across the ice into the goal because the force of gravity is acting perpendicular to the direction of motion. Work is defined as the product of force and displacement in the direction of the force. In this case, the force of gravity is acting vertically downwards, while the displacement of the puck is primarily in the horizontal direction. Since the force and displacement are perpendicular to each other, the work done by gravity is zero.