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A horizontal force pulls a 20 kg box across the floor with constant speed, is .60.

How much work does F do in moving the cart 3.0 m?
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2 Answers

Assuming the coefficient of kinetic friction is 0.60...
Draw a free body diagram listing all forces (I can't really show that to you on here). Since the speed is constant, the acceleration must be zero and thus the net force must be zero, so the horizontal force F must be equal to the frictional force.
Frictional force will be equal to the normal force (equal to mg in this case), multiplied by the coefficient of kinetic friction:
F = Frictional force = umg
where u is the coefficient of kinetic friction, 0.6, m and g are mass and gravity.
F = 0.6*20*9.8 
Now just use
Work = F*displacement
where displacement is 3 m.
Dear Sierra,
Without knowing what units the speed is being measured in (cm/sec)?, (feet/sec)? (furlongs per fortnight)? I can't help you.  Please clarify.