Can work ever be negative? If so, give an example of a force that produces negative work. (i) Instructions

Work can be negative when the force applied on an object and the displacement of the object are in opposite directions. In such cases, the angle between the force and displacement is greater than 90 degrees, resulting in negative work.An example of a force that produces negative work is friction. When an object slides on a surface, the frictional force acts in the opposite direction to the displacement of the object. For instance, when a book slides down a hill, the frictional force between the book and the surface of the hill acts upward, opposing the downward displacement of the book. Since the force of friction and the displacement of the book are in opposite directions, the work done by friction is negative.