Chapter 7.1, Problem 1AE

A box is dragged a distance d across a floor by a force ${\stackrel{\to }{F}}_{\text{P}}$ which makes an angle θ with the horizontal as in Fig. 7–1 or 7–3. If the magnitude of ${\stackrel{\to }{F}}_{\text{P}}$ is held constant but the angle θ is increased, the work done by ${\stackrel{\to }{F}}_{\text{P}}$ (a) remains the same; (b) increases; (c) decreases; (d) first increases, then decreases.