A 2.20 kg pendulum starts from a height of 5.00m. It swings back and forth through one whole oscillation but only returns to a maximum height of 4.75m. How much negative work was done on the pendulum during the first entire oscillation?

Answer 1

the "negative work" is equal to the lost potential energy due to the height difference

5.00 m g - 4.75 m g