Practice 9.1                                                                             Name ___________________________________


1. Define each of the following terms, and write the equation for each.

a. work

b. power

c. mechanical advantage

2. Explain the relationship between work and power.

3. Explain how machines make work easier if they still require that the same amount of work be done.

4. Calculate the amount of work done when a grocery store stocker uses 120 N of force to lift a sack of flour 1.5 m onto a shelf.

5. Calculate the average power in watts required to pull a car up a ramp if the amount of work is 250 kJ over a period of 45 s.

6. Calculate the mechanical advantage of a group of pulleys used to raise an engine from a car. The engine is raised 1.2 m with the pulleys when 4.8 m of rope is pulled through the pulleys.

7. Define potential energy

8. Define gravitational potential energy and give its equation.

9. Calculate the potential energy of a 4000 N car at the top of a 30 m hill.