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A block of weight 150N is pulled 20m along a horizontal surface at constant velocity. Calculate the work done by the pulling force if the coefficient of kinetic friction is 0.2 and the pulling force makes an angle of 600 with the vertical.

Given, (need figure)

Weight of block (W) = mg = 150 N
Workdone (W)=?
The verical and horizontal components of pulling force F are Fcosθ and Fsinθ. Then,
R+F.cos60=mg
or, R = mg - Fcos60 .......... (i)
        =150F2
Also,

μ=F.sin60R
R=F.320.2 .......... (ii)
From equation (i) and (ii), we get
or, 150F2=30.4F
or, F=31.056N
Then work done is,
W=F.sin6020=537.9J


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