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 6.4 eTest
70% Correct of 10 Scored items:
7 correct: 70%
3 incorrect: 30%
Submitted on December 12, 2012 at 8:24 PM (UTC/GMT)
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Question 1
Which of the following is not an expression of power?
Correct:
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Question 2
Use the following information to answer the next 2 questions.
A forklift raises a pallet full of goods weighing a total of 700 kg to a shelf 2.00 m high in 30.0 s.
What is the forklift's power output?
Correct: 458 J/s
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Question 3
If the forklift's motor must generate 550 W of power to lift the pallet, what is the motor's efficiency?
Incorrect: 46.0 %
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Question 4
Use the following information to answer the next 2 questions.
Quads are a common source of recreation in Alberta.
A particular quad with a mass of 300 kg is driving up a sand dune at a constant speed of 5.60 m/s. The force of resistance opposing its motion generated due to friction is 150 N. The dune's slope is 9.00° .
What is the forward force needed to maintain the quad's speed?
Correct: 610 N
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Question 5
Assume all the power output of the quad's engine goes into driving the quad up the slope. What is the power output of the quad's engine?
Incorrect: 2.58 kW
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Question 6
What is the relationship between the amount of work done and the power output of a machine?
Correct: Power is the rate of work being done.
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Question 7
Many trucks are equipped with winches. These winches are motor-powered spools that can be latched onto heavy objects, making it possible to pull them easily.
What is the relationship between the speed that an object is pulled by a winch and the power required by the motor to move the object?
Correct: As the speed of pulling increases, the power required increases.
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Question 8
Use the following information to answer the next 2 questions.
An empty elevator in a hotel (EL1) has a mass of 900 kg. It goes up to the 30th floor of a building, a total distance of 90.0 m, in 120 s. A freight elevator (EL2), with a mass of 2900 kg, goes up 4 floors in a building, a total distance of 12.0 m, taking 360 s.
What are the two elevators' power outputs?
Incorrect: EL1 is 675 W and EL2 is 6.40 x 104 W
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Question 9
If the freight elevator (EL2) goes up 10 floors (30.0 m) in 900 s, how does its power output change?
Correct: Its power output doesn't change.
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Question 10
A car engine is rated at 350 hp (1 hp = 746 W). How much work can it do in 30.0 min if its engine efficiency is 70%?
Correct: 3.29 x 108 J
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