1. Use the following information to answer parts a-b.

A 13.6 kg shelf is held 1.50 m above the ground for 25.0 s while it is screwed in to the wall.

a) What is the potential energy of the shelf with respect to the ground?

b) How much work is done on the shelf in this time?

2. An 80.0 kg office worker takes the stairs rather the elevator to his cubicle on the 14th floor. Each storey/floor is 4.35 m tall. If he walks at a constant velocity, how much work does he do on his body? Assume the ground level is the 1st floor.

3. Use the following information to answer parts a-b.

A student and her bicycle have a combined mass of 75.0 kg. She accelerates from rest to a velocity of 5.75 m/s in 15.0 s.

a) How much work has she done accelerating her bicycle?

b) What is the kinetic energy of the bicycle system after the acceleration?

4. Two people each exert a force of 300 N, pulling a car by separate ropes in the East direction. The first person pulls at an angle of 20.0 N of E, and the second person pulls at an angle of 20.0 S of E. Calculate the work done on the car by each worker if the car moves 0.50 m/s for 5.6 s.

6. You have an apple that you would like to weigh, but you don't have a scale. You do have a slinky and a quick internet search tells you that it has a spring constant of 10.0 N/m. You hang the apple from the slinky and measure that the slinky stretches 9.92 cm. What is the mass of the apple?

7. A spring with a spring constant of 45.5 N/m is stretched so that it has 2.275 J of

potential energy. How far was the spring stretched?

8. Use the following information to answer parts a-b.

In an experiment to test Hooke's Law, a student measures the displacement of a spring with varying masses. His data is shown below: