Question Detail
Question
What is the work done by the gravitational force on an object of mass m that is lowered vertically by a distance h?
Correct Answer
Option C is the correct answer.
Detailed Explanation
When an object is lowered, the force of gravity (mg downward) and the displacement (downward) are in the same direction. The angle between them is 0°, so cos 0° = 1. Therefore, the work done by gravity is W_g = F d cos θ = (mg)(h)(1) = +mgh.
Hint
Consider the direction of the gravitational force relative to the direction of motion.