A horizontal force `F` is applied such that the block remains stationary because `N` will produce torque.
The torque produced by friction force is equal and opposite the torque produce due to normal reaction (N).
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Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Answer

A

Explanation

(a) As the block remains stationary
`Sigma fx = 0 i.e., F = N`
`Sigma fy = 0 i.e., f = mg`
and `Sigma tau = 0` i.e., :. `vec tau _f + vec tau_N = 0`
As `vec tau_f ne 0` :. `vec tau_N ne 0` and torque by friction and normal reaction will be in opposite.
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