1- The graph shows how the force component F cos ? along the displacement varies

Question

1- The graph shows how the force component F cos ? along the displacement varies with the magnitude s of the displacement. If Fmax = 65.0 N and smax = 1.60 m, find the work done by the force. (Hint: Recall how the area of a triangle is related to the triangle's base and height.)

2- Starting from rest, a 91-kg firefighter slides down a fire pole. The average frictional force exerted on him by the pole has a magnitude of 815 N, and his speed at the bottom of the pole is 3.0 m/s. How far did he slide down the pole?

Explanation / Answer

For a the work is a +93J

For b it is 0

For c Use work -energy where W = change in kinetic energy

So W = Kf - Ki Ki =1/2*m*v^2 = 1/2*66*2^2 = 132J

The total work done is 93J

So K f = 93 + 132 = 225J

This = 1/2*m*v^2 so v final is v = sqrt(2*K/m) = sqrt(2*225/66) = 2.61m/s

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