Question
Thu December 29, 2011 By:

Solve the following question:

Expert Reply
Thu December 29, 2011
 
we will chose the x axis to be along the wedge since motion is possible in this direction only. Let us call the force required to just push it up the place and the force required to just prevent it from sliding down as . We need to draw the free body diagrams in both cases:
 
 

In the first case, friction acts to prevent from driving the mass up the plane. In the second case, friction helps to balance out gravitational force. In both cases

Balancing the forces along the x axis for both cases (remember that there is no acceleration hence net force is zero)

Dividing the equations, we get

Solve to get and N = 5. Keep in mind that this N has nothing to do with the normal force. This is simply a quantity defined in the question as 10 times

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