1. How much work is required to stop an electron (m = 9.11 10^-31 kg) which is moving with a speed of 1.97 10^6 m/s?
2. An automobile is traveling along a highway at 91 km/h. If it travels instead at 100 km/h, what is the percent increase in the automobile's kinetic energy?
3. A baseball (m = 145 g) traveling 25 m/s moves a fielder's glove backward 25 cm when the ball is caught. What was the average force exerted by the ball on the glove?
4. At an accident scene on a level road, investigators measure a car's skid mark to be 58 m long. It was a rainy day and the coefficient of friction was estimated to be 0.36. Use these data to determine the speed of the car when the driver slammed on (and locked) the brakes.
5. A sled is initially given a shove up a frictionless 26.0° incline. It reaches a maximum vertical height 1.35 m higher than where it started. What was its initial speed?
6. In the high jump, the kinetic energy of an athlete is transformed into gravitational potential energy without the aid of a pole. With what minimum speed must the athlete leave the ground in order to lift his center of mass 1.95 m and cross the bar with a speed of 0.56 m/s?
6 answers