1. A 2-kg bowling ball sits on top of a building that is 40 meters tall. (5 pts) Circle one: KE / GPE / both ( can you show work on how you got it) 2. . A 2-kg bowling ball rolls at a speed of 5 m/s on the roof of the building that is 40 tall. (5 pts) Circle one: KE / GPE / both 3.3. A 2-kg bowling ball rolls at a speed of 10 m/s on the ground. (5 pts) Circle one: KE / GPE / both 4. 1. A 1,000-kg car has 50,000 joules of kinetic energy. What is its VELOCITY? 5. 2. A 200-kg boulder has 39,200 joules of gravitational potential energy. What HEIGHT is it at? 6. 3. A 1-kg model airplane has 12.5 joules of kinetic energy and 98 joules of gravitational potential energy. What is its speed? What is its height?
Potential energy is energy due to an object's height above the ground. Potential energy = mass x gravity x height Kinetic energy is energy due to the motion of the object. Kinetic energy = 1/2 x mass x velocity²
1. The ball is not moving and is at a height above the ground so it has only potential energy. P.E = 2 x 9.81 x 40 P.E = 784.8 J
2. The ball is moving and has a height above the Earth's surface so it has both kinetic and potential energy. P.E = same as part 1 = 784.8 J K.E = 1/2 x 2 x 5² K.E = 25 J
3. The ball has no height above the Earth's surface and is moving so it has only kinetic energy. K.E = 1/2 x 2 x 10² K.E = 100 J
4. 50000 = 1/2 x 1000 x v² v = 10 m/s
5. 39200 = 200 x 9.81 x h h = 20.0 m
6. 12.5 = 1/2 x 1 x v² v = 5 m/s 98 = 1 x 9.81 x h h = 10.0 m
