1. A truck is traveling horizontally to the right (Fig. 4-38).When the truck starts to slow down; the crate on the (frictionless) truck bed starts to slide. In what direction could the net force be on the crate?

(a) No direction. The net force is zero.
(b) Straight down (because of gravity).
(c) Straight up (the normal force).
(d) Horizontal and to the right.
(e) Horizontal and to the left.
2. A bear sling, Fig. 4-40, is used in some national parks for placing backpackers' food out of the reach of bears. As the backpacker raises the pack by pulling down on the rope, the force F needed:

(a) Decreases as the pack rises until the rope is straight across.
(b) Doesn't change.
(c) Increases until the rope is straight.
(d) Increases but the rope always sags where the pack hangs.