A block of mass m is at rest under the action of force F against a wall as shown in figure. Which of the following statement is incorrect?

Options

A. `F =mg` [where f is the friction force]
B. `F =N` [where `N` is the normal force]
C. `F` will not produce torque
D. `N` will not produce torque

Answer

c,d

Explanation

The various forces acting on the block are shown in As the block remains stationary under the effect of these force so mg = f (force of friction)
`F = N` (Normal reaction) Torque due to `F` or mg is zero as the line of action of `F` or mg passes through center `C` Since the body is in equilibrium so the sum of torque due to force
of friction `(vec(tau_(f)))` and torque to normal reaction
`(vec(tau_(N)))` must be zero `vec(tau_(f)) + vec(tau_(N)) =0` As line of
action `vec(f)` and `vec(N)` may not pass through centre `C` of block so `vec(tau_(f))` may not be zero and ` vec (tau_(N))` may
also not be zero Therefore `vec(f)` does not produce
any torque is wrong and `vec(N)` does not produce a torque is also wrong .