PES Skill Sheets.book - Capital High School

Skill Sheet 7.2: Energy Transformations—Extra Practice
Part 1 answers:
1. The potential energy of the stretched bungee cord is changed
into the kinetic energy of the person bouncing back up.
2. The potential energy of the football from its high point is
changed into kinetic energy as it spirals down.
3. In this case, radiant energy is converted to chemical energy in
the battery, which is then converted to the electrical energy
needed to run the calculator. Mechanical energy (kinetic or
potential, is not being used in this case.
Part 2 answers:
1. The chemical potential energy of the wood is changed to
radiant energy in the form of heat. Radiant energy is changed
Skill Sheet 7.2: Conservation of Energy
1. 0.20 meters
2. 3.5 m/s
3. 39.6 m/s
4. 196,000 joules
Skill Sheet 7.2: James Joule
1. Perhaps because he thought that the pursuit of science was
worthwhile.
2. His father hired one of the most famous scientists of his time
to tutor his sons.
3. His interest was based upon his desire to improve the
brewery. He wanted to make a more efficient electric motor to
replace the old steam engines that they had at the time.
4. His goal had been to replace the old steam engines with more
efficient electric motors. He was not able to do that, however,
he learned a great deal about electromagnets, magnetism,
heat, motion, electricity, and work.
5. Electricity produces heat when it travels through a wire
because of the resistance of the wire. Joule’s Law also
provided a formula so that scientists could calculate the exact
amount of heat produced.
Skill Sheet 7.3: Efficiency
1. 27.1 percent
2. 92 joules
3. 100,000 joules
4. 94.2 kilojoules
Skill Sheet 7.3: Power
1. 250 watts
2. 50 watts
3. 1,200 watts
4. 1,500 watts
5. 741 watts
6. 720 watts
7. work = 500 joules; power = 33 watts
8. 1,800 seconds or 30 minutes
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into mechanical energy as the water boils, changes to steam,
and makes the whistle vibrate, which causes vibrations in air
molecules that we experience as sound.
2. Nuclear energy is changed into electrical energy, which is
changed into radiant energy (light to make the television
picture) and mechanical energy (vibration of speakers) that
causes vibration of air molecules that we experience as sound.
3. The chemical potential energy of food is changed into
mechanical energy of the bicyclist, which is changed into
electrical energy of the generator, which is changed into
radiant energy from the light.
5. 10. meters
6. 30. meters
7. Answers will vary.
6. Joule believed that heat was a state of vibration caused by the
collision of molecules. This contradicted the beliefs of his
peers who thought that heat was a fluid.
7. Joule knew that the temperature of the water at the bottom of
the waterfall was warmer than the water at the top of the
waterfall. He thought that this was true because the energy
produced by the falling water was converted into heat energy.
He wanted to measure how far water had to fall in order to
raise the temperature of the water by one degree. Joule used a
large thermometer to measure the temperature at the top of
the waterfall and the temperature at the bottom of the
waterfall. The experiment failed because the water did not fall
the right distance for his calculations and there was too much
spray from the waterfall to read the instruments accurately.
8. Refrigeration
9. The joule is the international measurement for a unit of
energy.
10. Answers will vary.
5. Answers are:
a. 2,025 million watts
b. b. 39.5 percent
6. 59 percent
9. 2,160,000 joules
10. 2,500 watts
11. 90,000 joules
12. work = 1,500 joules; time = 60 seconds
13. force =25 newtons; power = 250 watts
14. distance = 100 meters; power = 1,000 watts
15. force = 333 newtons, work = 5,000 joules