question_answer

Direction for: In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as

Assertion: Angle of repose is equal to the angle of limiting friction. Reason: When the body is just at the point of motion, the force of friction in this stage is called limiting friction.

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.

Correct Answer: B

Solution :

At the point of a rough contact where slipping is about to occur, the two forces acting on each object are normal reaction N and frictional force \[\frac{1}{4}\]. Thus, limiting angle \[\frac{1}{2}\] or   \[\sqrt{2}{{I}_{AC}}={{I}_{EF}}\]                  ?..(i) Now, at the point of sliding down the angle of inclination of the plane with the horizontal is called the angle of repose \[(\alpha )\]. From figure \[{{I}_{AD}}=3{{I}_{EF}}\] or  \[{{I}_{AC}}={{I}_{EF}}\] or   \[{{I}_{AC}}=\sqrt{2}{{I}_{EF}}\]                     ?.(ii) From Eqs. (i) and (ii) \[{{R}_{L}}\]