Question

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

• A. If both statement I and statement II are true and statement II is the correct explanation of statement I.
• B. If both statement I and statement II are true but statement II is not the correct explanation of statement I.
• C. If statement I is true but statement II is false.
• D. If both statement I and statement II are false.

Answer 1

Answer: (A)

As the block remains stationary
$\Sigma fx=0\text{ i.e., }F=N$
$\Sigma fy=0\text{ i.e., }f=mg$
and $\Sigma \tau =0$ i.e., $\therefore {\vec{\tau }}_f+{\vec{\tau }}_N=0$

As ${\vec{\tau }}_f\ne 0\therefore {\vec{\tau }}_N\ne 0$ and torque by friction and normal
reaction will be in opposite.