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Old Apr 7th 2012, 04:35 AM   #1
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Question Work done by friction (object pulled at constant velocity)

My problem in understanding work done by friction proceeds reading about dissipative forces.

Dissipative forces transform kinetic energy to thermal energy.

Let the situation be that a box is pulled across a surface at constant velocity. Knight on p320 argues that since kinetic energy is unchanging, thermal energy is coming from "the work done on the system by the tension in the rope".

But then how is there a K -> E_th?
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Old Apr 7th 2012, 09:44 PM   #2
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I guess the thermal energy would be lost by means of friction in reality for the one/ for the machine that keeps the box at constant velocity. That is tension in the rope is first changed to friction and then to thermal energy.

But you may question that if i assume that no friction exists in all surfaces, what would be the transformation? For this one, i suspect whether in reality someone can mimic that experiment. Otherwise, it would be quite impossible for us to have a conclusion
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Old Apr 19th 2012, 08:20 AM   #3
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Similar Calculation might help.

This example which is similar to yours:


Might be of interest. Good Luck, JP
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  Physics Help Forum > High School and Pre-University Physics Help > Kinematics and Dynamics

constant, constant speed, constant velocity, friction, object, pulled, velocity, work

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