# A block of 20 kg mass is being pulled up a slope making angle 30° with horizontal by applying force of 150 N acting parallel to slope. Calculate work done by applied, frictional and net force in pulling the load up a distance of 3 m. Coefficient of friction between block and slope is 0.2.

The mass of the block is 20 kg and applied force is 150 N .Now , distance travelled by the block is 3 m and coefficient of friction is 0.2.

Now work done by applied force is ,

${W}_{1}=Fs\mathrm{cos}\theta =150\times 3\times \mathrm{cos}30\xb0=389\xb77J$

Now again frictional force acting on the block is ,

${F}_{r}=\mu Mg\mathrm{cos}30\xb0=0\xb72\times 20\times 9\xb78\times \frac{\sqrt{3}}{2}=39\xb72\times \frac{\sqrt{3}}{2}N$

So the work done due to frictional force is ,

${W}_{2}=\mu Mg\mathrm{cos}30\xb0\times s=39\xb72\times \frac{\sqrt{3}}{2}\times 3=101\xb784J$

Now the net work done to pull the block upwards overcoming the frictional force is ,

${W}_{net}={W}_{1}-{W}_{2}=389\xb77-101\xb784=287\xb785J$

Regards

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