Student Email: 1024885@wells-school.com
Site Title: Pearson Physics - Welcome to the eTest Companion Site
Location on Site: U3: Circular Motion, Work, and Energy > Chapter 6 > Section 6.3 eTest
80% Correct of 10 Scored items:
8 correct: 80%
2 incorrect: 20%
Submitted on December 12, 2012 at 8:16 PM (UTC/GMT)
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Question 1
Which of the following statements about an isolated system is false?
Correct: Objects in an isolated system can be subject to heat loss due to friction.
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Question 2
Which of the following correctly describes the law of conservation of energy?
Correct: In terms of mechanical energy, any gain in kinetic energy must be accompanied by an equal loss in potential energy.
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Question 3
The following graph illustrates the mechanical (EM), potential (EP), and kinetic (EK) energies for a block sliding down an inclined plane.
Which of the following best describes the changes in energy involved in this situation?
Incorrect: The sum of EP and EK must equal zero in this isolated system.
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Question 4
Hang-gliding is a popular sport that represents energy changes very well. As a hang-glider gains altitude, potential energy is gained. As the hang-glider gains velocity, kinetic energy is gained.
Assume that a hang-glider with a mass of 140 kg represents an isolated system. At one point the hang-glider has a speed of 10.0 m/s and is 200 m above the ground. Later, he/she is going 15.0 m/s. What is the gravitational potential energy when he/she is moving 15.0 m/s?
Correct: 2.66 x 105 J
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Question 5
Which of the following most closely resembles an isolated system?
Correct: A metronome (a pendulum-like gadget used to keep time) on a piano
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Question 6
A swing is a good example of a system in which energy is readily converted from potential to kinetic. If the girl in the photo is pushed up in the swing, she gains potential energy. As she gains speed when she swings, she gains kinetic energy.
Which of the following statements best describes this swing system?
Correct: The system is not isolated, due to loss of energy in the form of heat.
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Question 7
Use the following information to answer the next 2 questions.
A pendulum is a good example of a system in which energy is readily converted from potential to kinetic. As the pendulum bob gains altitude, it gains potential energy. As the pendulum bob gains speed, it gains kinetic energy.
At which point of the pendulum bob's motion does kinetic energy equal zero?
Correct: Point A
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Question 8
At which point of the pendulum bob's motion is kinetic energy at a maximum?
Correct: Point B
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Question 9
An ideal pendulum is suspended by a string that is 1.00 m long. The bob of the pendulum is pulled sideways and released. At the highest point of its swing the pendulum bob is 10.0 cm above the floor. At the lowest point the pendulum bob is 2.00 cm above the floor. The pendulum bob's mass is 20.0 g. What is the pendulum bob's maximum speed?
Correct: 1.25 m/s
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Question 10
Consider a frictionless trolley car coming down either one of two routes from a mountain. The first route is straight down the mountain's steep slope. The second route is a gentle winding path around and around the mountain to the same bottom point as the first route. Which statement about this situation is true?
Incorrect: The trolley will be going much faster down the steeper route and therefore will be at a higher speed at the bottom point.
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