4. The 2000 kg cable car shown in figure descends a 200m high hill. In addition to its brakes, the cable car controls its speed by pulling an 1800 kg counterweight up the other side of the hill. Friction is negligible. a. How much braking force does the cable car need to descend at constant speed? b. One day the brakes fail just as the cable car leaves the top on its downward journey. What is the runaway car's speed at the bottom of the hill? 30° 200 m Counterweight 20°

4. The 2000 kg cable car shown in figure descends a 200m high hill. In addition to its brakes, the cable car controls its speed by pulling an 1800 kg counterweight up the other side of the hill. Friction is negligible. a. How much braking force does the cable car need to descend at constant speed? b. One day the brakes fail just as the cable car leaves the top on its downward journey. What is the runaway car's speed at the bottom of the hill? 30° 200 m Counterweight 20°