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Energy #1

Energy #1. 1. What ’ s the PE of a 142.3 kg rock located at a height of 8.4m above the floor? 2. How much work did it take to raise the rock to that height? 3. How much work could gravity do if it falls from the 8.4m height to the floor?

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Energy #1

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  1. Energy #1 1. What’s the PE of a 142.3 kg rock located at a height of 8.4m above the floor? 2. How much work did it take to raise the rock to that height? 3. How much work could gravity do if it falls from the 8.4m height to the floor? 4. If it fell and did work over 11.4 s, what was the power output of the rock?

  2. Energy #2 1. What is the PE of a high diver who has a mass of 50kg and is 80m above a pool? 2. How fast would she be going when she hits the pool? 3. As she falls through the air, her PE____, her KE ____, and her total mechanical energy_____

  3. Energy #3 A plane is carrying a 1966 apricot VW Beetle (m=1000kg), and is flying at an altitude of 4800m at 45 m/s. a.) What is the potential energy of the VW? b.) If the car is dropped out of the plane, what will be its vertical velocity when it hits the ground? c.) How many seconds will it fall? d.) How far horizontally will it travel during its fall? e.) How much work does the plane do on the car if it carries it for 3000m before dropping it?

  4. Energy #4 • How does the KE of an object going 5 m/s compare to the KE of an object going 10 m/s? • What happens to the KE of an object if its mass is tripled and the velocity stays the same? • What happens to the KE of an object if the mass is cut in half and the velocity doubles?

  5. Energy #5 • If the KE of a 9.2kg object is 627J, how fast is it going? • What’s the gravitational potential energy of a 2x106kg rock located on top of the head of a 16.4m high hampster? • If a 427kg watermelon has 6.32x107J of PE, how high is it?

  6. Energy #6 • What is the spring constant of a bungee cord if a 100kg person causes it to stretch 5m? (static weight, not falling) • What’s the elastic PE in a spring (k=1.4N/m) that is stretched 0.82m?

  7. Energy #7 • If a force of 23N stretches a spring 0.54m, what is the spring constant? • A 2kg ball is placed in front of the spring above. How fast will the ball move when the spring is released?

  8. Energy #8 • An 800kg car is traveling 15m/s. Find the KE. • It comes to rest due to friction after 25m. How much work was done by friction? • What is the frictional force acting on the car?

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