A body of weight 64, N is pushed with just enough force to start it moving across a horizontal floor

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4-2.Friction

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A body of weight $64\, N$ is pushed with just enough force to start it moving across a horizontal floor and the same force continues to act afterwards. If the coefficients of static and dynamic friction are $0.6$ and $0.4$ respectively, the acceleration of the body will be (Acceleration due to gravity $= g$)

A

$\frac{g}{{6.4}}$

B

$0.64\, g$

C

$\frac{g}{{32}}$

D

$0.2\, g$

Solution

(d) Weight of the body $= 64\,N$

so mass of the body $m = 6.4\;kg$, ${\mu _s} = 0.6$, ${\mu _k} = 0.4$

Net acceleration $ = \frac{{{\rm{Applied\, force – Kinetic\, friction}}}}{{{\rm{Mass\, of\, the \,body}}}}$

$ = \frac{{{\mu _s}mg – {\mu _k}mg}}{m} = ({\mu _s} – {\mu _k})g = (0.6 – 0.4)g = 0.2\,g$

Standard 11

Physics

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