Question

Assertion: The acceleration of a body down a rough inclined plane is greater than the acceleration due to gravity.
Reason: The body is able to slide on a inclined plane only when its acceleration is greater than acceleration due to gravity.

• A. If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
• B. If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion
• C. If Assertion is true but Reason is false
• D. If both Assertion and Reason are false

Answer 1

Answer: (D)

Let a body which has mass $m$ is placed on an inclined plane whose inclination is greater than angle of repose. The force on the body down the inclined plane is given by
$F =m g \sin \theta-\mu R$
$m a =m g \sin \theta-\mu m g \cos \theta$
or $a =g \sin \theta-\mu g \cos \theta$
$=g(\sin \theta-\mu \cos \theta)$ ...(i)

It is obvious from Eq. (i) that $a