Name Section Period 7 Exercises: Work and Energy Write answers to the questions below. Show your mathematical steps and the units of the quantities. This sheet with your answers should be turned in at the beginning of Period 8. 1. Work done to store potential energy: The mass of a model pile driver like the one seen in class is raised to a height of 80 cm (0.80 m). The pile driver has a mass of 3.0 kg. a) Find the joules of gravitational potential energy of this raised pile driver mass. b) Assuming no energy was wasted, how many joules of work were needed to raise this mass to a height of 0.80 meters? 2. Equating kinetic and gravitational potential energy (metric units): A ball is thrown straight up with an initial velocity of 8.0 meters/sec. How high will the ball rise? (Ignore wasted energy.) 3. Equating kinetic and gravitational potential energy (English units): A playground slide with a vertical height of 6 feet is totally frictionless. What speed would a child have at the bottom of the slide? (Hint: If we ignore friction, the gravitational potential energy at the top of the slide equals the kinetic energy at the bottom. The acceleration of gravity, g, in English units = 32 ft/s.)