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Calculate work done to move a body of mass 10 kg along an incline $(\theta=30^{\circ})$ with constant velocity through a distance 10 m $(g=10 m/s^2)$

\[(a)\;1000 \;J \quad (b)\;500 \;J\quad (c)\;250\;J \quad (d)\;10\; J\]

Sir,but the total force on body will be zero and even the velocity is constant. So how could be work done a\c work enegy theorem?

1 Answer

We need to apply an external force, $F=mg \sin \theta$ up the plane, while the body is in motion downwards.
$\Rightarrow W = F\;d = mg \sin \theta \; d$
Given $d=10\;m, m = 10 Kg, \theta = 30^\circ, g = 10 m/s^2$,
$W=10 \times 10 \times \sin 30 \times 10$
$\quad=100 \times \large\frac{1}{2}$$ \times 10$
answered Jul 18, 2013 by meena.p
edited Aug 25, 2014 by balaji.thirumalai

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