Jacob M.

# A 50N sofa is inclined on a ramp at 250. Both µk and µs are 0.6

a.) What is the smallest force parallel to the incline needed to keep the sofa from sliding down?

b.) What parallel force is required to keep the sofa moving up the incline at a constant speed?

c.) Assume the force, F, up the incline is 94N. What is the acceleration of the object?

d.) From part c, how far will it move in 10s?

## 1 Expert Answer

By:

Arturo O.

I concur completely with Steven's analysis.  However, I suspect there is an error in the problem statement.  The coefficient of kinetic friction is always lower that the coefficient of static friction, so they cannot both be 0.6.   Typically, a coefficient of kinetic friction is of the order of 1/10 of the coefficient of static friction.  But Steven's analysis is correct for the problem as stated.

Jacob, could you double check the values of those two coefficients?
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10/14/16

Steven W.

tutor
I wondered the same thing, Arturo, though I suppose it is not beyond the pale for then to be equal. But the other thing that struck me was the 50 N weight for the sofa.  That means its mass is only about 5 kg. That is one light sofa!
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10/14/16

Arturo O.

Yes, it is a light sofa!  Maybe the problem should have stated a "block" instead of a sofa.
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10/14/16

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