Question

Force of magnitude 4.2 N is applied on block placed on rough horizontal
surface. If coefficient of friction between block and surface is 0.2, then
frictional force on the block will be

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Answer 1

Explanation:

Static friction is a self-adjusting force.

The limiting value of friction up to which the body stays at rest till it starts moving is given by, Fs=μmg

where μ is the coefficient of static friction.

Below that limit, the frictional force is equal to the force applied.

Here Fs=0.8×4×10=32N ;   g=10m/s2

Whereas force applied is 19N less than the limiting value of friction.

Hence Frictional force is 19N.   

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