Name______Date______Period____

Work and Power

Pre-Lab

Part I: WORK

1.What is work?

2.How are force, work, and distance related?

3.What are the units of work?

4.A 900 Newton mountain climber scales a 100 meter cliff. How much work is done by the mountain climber?

Part II: POWER

1.What is power? What is the relationship among power, work, and time?

2.What is watt?

3.A small motor does 4000 Joules of work in 20 seconds. What is the power of the motor in watts?

4.Suppose you ride in a sleigh being pulled by horses at 16 kilometers per hour. Another sleigh being pulled at 10 kilometers per hour travels the same distance you do.

a.Which horses are more powerful?

b.How is speed related to power?

Part III: WORK and POWER Experiments.

Be sure to clearly explain your calculations by stating each formula you use and by showing what values you are substituting into each formula.

1.How much work it take to lift

a.a 1.0 kg mass from the floor to your partner's waist?

b.a 0.5 kg mass from the floor to your partner's waist?

c.a 1.0 kg mass from the floor to your partner's head?

d.a 0.5 kg mass from the floor to your partner's head?

2.Which of the four actions in #1 required the most work? Why?

3.How much power do you exert when you lift

a.a 1.0 kg mass from the floor to your partner's waist?

b.a 0.5 kg mass from the floor to your partner's waist?

c.a 1.0 kg mass from the floor to your partner's head?

d.a 0.5 kg mass from the floor to your partner's head?

4.In which of the four actions in #3 did you exert the most power? Why?

5.Demonstrate and explain how the action in #3(b) could actually be done with more power than the action in #3(c).

6.Could the action in #3(b) actually be done with more work than the action in #3(c)? Explain.

Part IV: Doing Work on Yourself

Be sure to clearly explain your calculations by stating each formula you use and by showing what values you are substituting into each formula.

1.How much force do you have to exert in order to climb onto your chair?

a.Answer in pounds.

b.Answer in newtons.

2.How much work do you do when you climb onto your chair?

3.How much work do you do to climb the stairway?

a.Answer in joules.

b.Answer in food Calories. (One food Calorie is equal to 4180 joules.)

4.Which student in the class do you think exerted the least work to climb the stairway? Why?

5.How much power did you exert when you climbed the stairway?

a.Answer in watts.

b.Answer in horsepower. (One horsepower is 746 watts.)

6.Which person in your group exerted the most power? How?

7.How high can you climb on the energy from one M&M (18,000 joules)? Explain your work clearly.

8.How high can you climb on the energy from one Tootsie Roll (28 food Calories)? Explain your work carefully.