A snowball at the top of a mountain breaks in half. One half rolls down the left side and the other down the right side, as shown below. On which snowball does the earth do more work?

Two sleds slide down a mountain. One slides down in a curvy fashion while the other heads straight down the mountain, as shown below. On which sled do the small frictional forces do more work?

A 5,000kg helicopter flies at a constant speed and altitude. If the helicopter experiences 1,000N of wind resistance, how much work is done by the air pushing up (and forward) on the helicopter blades as it moves 100m?

A 5,000kg helicopter flies at a constant speed and altitude. If the helicopter experiences 1,000N of wind resistance, how much work is done by the earth on the helicopter as it moves 100m?

A ball on a spring swings around in a circle. As it swings once around, the spring stretches from its equilibrium length of 0.8m to a length of 1.2m. If the spring constant is 20N/m2, how much work is done by the spring on the ball as the ball swings once around?

The spring below is initially stretched 0.5m from its equilibrium length of 1m. When the ball is released, it moves a distance of 1m. What is the total work done on the ball by the spring?