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 = 1 m.

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 = 1 m.

Numerical

(a) –1 J

(b) –2 J

(c) –4 J

(d) –5 J

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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