Work, Power, Kinetic, and Potential Energy

 1.  A man weighing 750 N climbs a flight of stairs 5 m high. How much work has he done?

2.  If an 800 lb rock has a potential energy of 1.8 E 4 ft lb, how high above the ground must the rock be?

3.  Find the kinetic energy of a bullet weighing 0.10 N if its velocity is 2.0 E 3 m/s?

4.  How much work is done when a force of 25 N is used to slide a 150 N sofa 10 m across the floor?

5.  What horsepower engine is required to raise a man of 50 kg to a height of 10 in 15 seconds?

6.  A power shovel raised 500 lb of earth to a height of 12 feet in 7 seconds. What horsepower is used?

7.  An elevator in the Empire State building rises to the 80^th floor in 50 seconds. If the height is 989 feet, what horsepower must be developed in order to lift 12 people averaging 150 lb each to this floor?

8.  How many kilowatts are required to raise a weight of 30 N a distance of 10 m in 3 minutes?

9.  An object weighing 500 N strikes the earth with a velocity of 15 m/s.

     a) with what kinetic energy does it strike the earth

     b) from what height was it dropped

      c) what was the potential energy of the object before it was dropped

10.  A large rock with a mass of 10 kg rest on top of a cliff 130 m high.

      a) what is the potential and kinetic energies at time t = 0, t = 1 s, and just prior to impact with ground

      b) how long will it take the rock to fall to the ground

       c) how fast would the rock be traveling at impact