A 5.5-kg block is pushed 2.9 m up a vertical wall with constant speed by a const

Question

A 5.5-kg block is pushed 2.9 m up a vertical wall with constant speed by a constant force of magnitude F applied at an angle of

= 30°

with the horizontal, as shown in the figure below. If the coefficient of kinetic friction between block and wall is 0.30, determine the following.

(a) the work done by

J

(b) the work done by the force of gravity
J

(c) the work done by the normal force between block and wall
J

(d) By how much does the gravitational potential energy increase during the block's motion?
J

Explanation / Answer

in horizontal direction

N = Fcostheta

in y direction

Fsintheta - mg - f = 0

Fsin theta - mg - mu*N = 0

Fsin theta - mg - mu*Fcos theta

F = mg / sin theta - mu*costheta

F = 224.4 N

part a )

W = Fsintheta * d

W = 325.285 J

part b )

-mg*d = -5.5 x 9.8 x 2.9 = -156.31 J

part c )

0 there is no diplacement

part d )

U = mgh = 156.31 J

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