Q: A block of mass 1 kg is projected from point A along irregular rough inclined surface and reaches at the point B as shown in the figure. The coefficient of friction between the block and the inclined plane is 0.5. Find work done by the friction on the block if AC = 1m.
(a) -1J
(b) -2J
(c) -4J
(d) -5J
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Ans: (d)
Sol: Work done by friction
$ \displaystyle = – \mu m g cos\theta \times S $
$\displaystyle = – \mu m g (AC) $
$ \displaystyle = – 0.5 \times 1 \times 10 (1) $
= – 5 J