Practice 9.1 Name
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**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.