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Study Guide – Chapter 6
Write the proper units for each of the following:
1.
work
power
potential energy
kinetic energy
efficiency
gravity
2. Key Terms: know all of the following terms – YOU DON’T HAVE TO STAPLE THEM.
Work-energy theorem
Momentum
Watt
Machine
Efficiency
Conservation of energy
Work
Kinetic Energy
Law of Conservation of
Potential Energy
Power
Energy
Answer the following:
3. Give an example where two people do the same amount of work, but one more powerful than
the other.
4. Give an example where one person does more work than the other, but they
are equally powerful.
5. In your own words, explain the relationship between work and energy.
6. Explain how potential and kinetic energy relate to roller coasters.
7. For each statement, explain if work is being done, or explain why no work is
being accomplished.
a.
b.
c.
d.
e.
I carried my books upstairs to my bedroom.
The wind blew the lawn chair across the yard.
The wall in my classroom won’t budge no matter how much I push on it.
I blew some dust off my paper.
I stood very still and balanced a book on my head.
8. Calculate work and then power using the following
values for force and distance. Give your answers in
proper units.
a. 12 N lifted 5 meters in 10 s.
b. 3 N pushed 3 meters in 2 s.
c. 400 N dragged 10 meters in 14 s.
d. 7.5 N lifted 18.4 meters in 82 s.
Read each of the following and solve, but be sure of
what you’re solving for!!!
9. You want to prove the law of conservation of
energy to a friend. For your demonstration you
show that you can use a block and pulley machine to
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lift 100 N with only 20 N of input force. What would you say to your friend to explain how this is
possible?
10. A 90.0 kg rock climber ascends 45.0 meters up to the top of a quarry, and then descends 85.0
meters from the top of the quarry to the ground. Find the potential energy of the climber at the
top relative to his starting position.
11. John has an object suspended in the air. It has a mass of 50 kilograms and is 50 meters above the
ground. How much work would the object do if it was dropped?
12. A rifle can shoot a 4.20 gram bullet at a speed of 965 m/s. What is the kinetic energy of the bullet
when it leaves the rifle?
13. Tarzan, with a mass of 75.0 kg, swings down from a tree limb on the end
of a vine. His feet touch the ground 4.00 meters below the tree limb. He
swings at the speed of 10 m/s. What is Tarzan’s kinetic energy?
14. You have a machine that tells you exactly how much work in joules is put
into a machine and how much work was produced. The readings that you
just received from the machine state that the input work was 345 joules and the output work was
330 joules. The law of conservation of energy states that input should equal output. How can you
explain the “lost” 15 joules?
15. The manufacturer of a machine said that it is 86 percent efficient. If you use 70 joules to run the
machine (work you do), how much output work will it produce?
16. A machine is 72 percent efficient. If it produces 150 joules of work output, how much work was
put into the machine?
17. What are some different types of energy, where do they come from, and what is meant by
transformations of energy?
18. Explain the energy transformations in the following:
a. hairdryer
c. car
b. toaster
d. a sandwich
e. light bulb
f. glow stick
Directions: Using the diagram to the right, answer
the questions.
19. Identify at which point the cart will have the
most kinetic energy.
20. Identify at which point the cart will have the
most potential energy.
21. Compare the kinetic and potential energy at
point C to the other points on the track.
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Big and Meaty are watching Rob skateboard. Big has a mass of 192 kg and is sitting on a seat that is
1.75 meters high. Rob has a mass of 61 kg and is moving at 2 m/s. Meaty is being held by Big. He
weighs only 26 kg and is 2 meters off the ground.
22. What is the potential energy of Meaty?
23. What is the kinetic energy of Rob?
24. At the end of the ride up a steep hill, Ken was at an elevation of 1,600 meters above where he
started. He figured out that he and his bicycle had accomplished 1,000,000 joules of work. If Ken
has a mass of 54 kg, what is the mass of his bicycle? (CHALLENGE!)
25. Write five different situations showing different energy transfers in each one. Underline the
types of energy.
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