7.1 Work: The Scientific Definition

Given the table about how much force does the rocket engine exert on the 3.0-kg payload?

1. 150 N
2. 300 N
3. 450 N
4. 600 N

Look at the reference(c). You compress a spring by x, and then release it. Next you compress the spring by 2x. How much more work did you do the second time than the first?

1. Half as much
2. The same
3. Twice as much
4. Four times as much

How much work does a supermarket checkout attendant do on a can of soup he pushes 0.600 m horizontally with a force of 5.00 N? Express your answer in joules and kilocalories.

(a) Calculate the work done on a 1500-kg elevator car by its cable to lift it 40.0 m at constant speed, assuming friction averages 100 N. (b) What is the work done on the elevator car by the gravitational force in this process? (c) What is the total work done on the elevator car?

A shopper pushes a grocery cart 20.0 m at constant speed on level ground, against a 35.0 N frictional force. He pushes in a direction $\text{25} . 0 º$ below the horizontal. (a) What is the work done on the cart by friction? (b) What is the work done on the cart by the gravitational force? (c) What is the work done on the cart by the shopper? (d) Find the force the shopper exerts, using energy considerations. (e)…