An eraser with a mass of 100 g sits on a book at rest. The eraser is initially 10.0 cm from any edge of the book. The book is suddenly yanked very hard and slides out from under the eraser. In doing so, it partially drags the eraser with it, although not enough to stay on the book. The coefficient of kinetic friction between the book and the eraser is 0.150.
(a) The sign of the work done by the force of kinetic friction of the book on the eraser is (1) positive, (2) negative, or (3) zero work is done by kinetic friction. Explain.
(b) How much work is done by the book’s frictional force on the eraser by the time it falls off the edge of the book?