| Walt is
pushing this 2000-N refrigerator up the ramp. Unfortunately, he seems more
interested in our photographer than where he is going. If he doesn't straighten
out soon, this will turn into a falling-body problem!
The ramp makes an angle of 20° with the horizontal. Because the cart has a coefficient of friction of only 0.05, most of Walt's push is against the gravitational component. If Walt is pushing parallel to the ramp, what force must he exert to keep the refrigerator moving up at a constant velocity? |
The parallel and normal components
of the refrigerator's weight are:
(2000 N)sin 20° = 684 N and (2000 N)cos 20° = 1880 N, respectively. If there were no friciton, Walt would have to push with 684 N of force. Friction adds 0.05(1880 N) = 94 N for a total of 778 N, the required force. |