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Physics Review Question
Unit: Mechanics
Year: 1988 Question#: 17
Question: Work is done when a force _______
(1 ) acts vertically on a cart that can
only move horizontally
(2 ) exerted by one team in a tug of war
when there is no movement
(3 ) is exerted while pulling a wagon up
a hill
(4 ) of gravitational attraction acts on
a person standing on the surface of the Earth
What is this question really asking?
Explanation by: Sadia A (partially)
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Answer 1
acts vertically on a cart that can only move horizontally
INCORRECT
This is not the answer because although there is a force being exerted,
the cart is not moving. No work is being done on the cart because there
is no change in the displacement in the direection of the motion. return to top
Answer 2
exerted by one team in a tug of war when there is no movement
INCORRECT
Although there is a force exerted by each team on either side of the rope,
there is no change in the displacement. The rope does not achieve an actual
change in the displacement.
return to top
Answer 3
is exerted while pulling a wagon up a hill
CORRECT
This is the correct answer beacause in addition to there being a force exerted
on the actual wagon, the wagon is also moving. There is a change in the
displacement that is being caused by the force.
return to top
Answer 4
of gravitational attraction acts on a person standing on the surface of
the Earth
INCORRECT
This is not the right answer the person is not actually moving - there is
no change in the displacement. Although the gravitational force is pulling
the person toward the ground, the person has not actually moved anywhere
as a result of that force.
return to top
What's this question really asking?
What situations really involve work? Or ...in what situations does the force
cause a motion parallel to the force?
return to top
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