1. A 75 kg bobsled is pushed along a horizontal surface by two athletes. After 4.5 m from rest, the bobsled has a speed of 6.0 m/s. How much force did the two athletes push with?
2. In 1990, Roger Hickey, 74 kg, of California reached a speed of 35 m/s (77 mph) on his skateboard, 3.6 kg. How much force would be needed to stop him in a distance of 150 m (about half a football field)?
3. A car that weighs 14700 N is traveling at 25 m/s. The brakes are applied and the car stops. The braking force is -7100 N. What was the braking distance?