Dont understand physics work question?

In summary, a person applies a constant force to an object of mass 20 kg, causing it to move horizontally at a constant speed of 0.20 m/s through a distance of 0.80 m. The question asks for the work done on the object, and the answer is 0J. This is because the force counteracting gravity is perpendicular to the displacement, and the object is moving at a constant speed with no friction. Therefore, there is no change in kinetic energy and no work done on the object.
  • #1
elpermic
29
0

Homework Statement


its for me midterm..

a person applies a constant force on an object of mass 20 kg that causes the object to move horizontally at a constant speed of 0.20 m/s through a distance of 0.80m . What is the work done on the object?

A) 0J
B) 10J
c)16J
d)160jNow the answer is 0J. But I don't understand why.. THe professor says its 0J and his reason is "Force counteracting gravity is perpendicular to the displacement."

Homework Equations


The Attempt at a Solution


is it because the question is saying what is the work done by the object?? because it doesn't say what's the work done on the object by the person..
 
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  • #2
elpermic said:
Now the answer is 0J. But I don't understand why.. THe professor says its 0J and his reason is "Force counteracting gravity is perpendicular to the displacement."
Given what your professor said, I gather we are supposed to ignore friction. So, ignoring friction,...

The object is moving at a constant speed. What is the acceleration of an object moving at a constant speed?

Applying Newton's second law, what is the force on an object that is moving at a constant speed (and remember, for this problem we are assuming 0 friction)?

Thus the work done on that object is...?
 

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