Physics Review Question

Unit: Work and Energy
Year: 1993 Question#: 19
Question: A net force of 5.0 newtons moves a 2.0 kilogram object a distance of 3.0 meters in 3.0 seconds. How much work is done on the object?
(1 ) 1.0 J
(2 ) 10. J
(3 ) 15 J
(4 ) 30 J

What is this question really asking?


Explanation by: Jennifer I

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Answer 1
1.0 J

INCORRECT
1.0 J can be obtained by dividing the distance by the time. This would be the speed of the object. It is not related to the work done on the object. Try using W=Fd return to top























Answer 2
10. J
INCORRECT
This answer can be obtained by multiplying the newton force, the distance travelled by the object and the mass of the object. This number can then be divided by the time it took to move the object. The mass of the object and the time it takes to move the object are irrelevant for the work done on the object and the answer does not produce units for joules.
Try using W=Fd return to top



























Answer 3
15 J

CORRECT
Work = Fs
Work = (50N)(3.0m)=15 Nxm = 15 joules.
The mass of the object and the time to move the object do not matter in this problem. return to top


























Answer 4
30. J
INCORRECT
This answer can be found by multiplying the newton force, the distance the object was moved and the mass of the object. This answer does not lead to the correct units (joules) because the mass of the object is irrelevent in this problem.
Try using W = Fs return to top


t























What's this question really asking?
How much work is done on a 2.0 Kg object that is moved 3.0 meters in 3.0 seconds by a force of 5.0 Newtons.
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