Question

Assertion: If the earth suddenly stops rotating about its axis, then the value of acceleration due to gravity will become the same at all the places on the surface of the earth.
[Assume earth as a perfect sphere]
Reason: The value of acceleration due to gravity is independent of the rotation of the earth
A. Both Assertion and Reason are correct and the reason is the correct explanation for assertion
B. Both assertion and reason are correct but the reason is not the correct explanation for assertion
C. The assertion is correct but the reason is incorrect
D. The assertion is incorrect but the reason is correct

Answer 1

Hint: zAcceleration due to gravity is the acceleration experienced by a body falling freely towards the earth. The value of acceleration due to gravity is usually taken as a constant. But there is a slight variation of acceleration due to gravity from place to place depending on the depth or height of the place.

Complete step by step answer:
Due to the rotation of the earth, there is a centrifugal force that is supplied by the gravitational force of the earth. This is directed towards the centre of the earth. Centrifugal force is an inertial force according to Newtonian mechanics. The acceleration due to gravity has the highest value at the poles due to the non-spherical shape of the earth and the centrifugal force. The value is minimum at the equator due to the same reason. Here we assume the earth to be a perfect sphere. Therefore when the rotation of the earth stops there will not be any centrifugal force. Therefore there will not be any factors that affect the acceleration due to gravity at different places. Therefore the value of acceleration due to gravity will be the same throughout the earth. Therefore the assertion is correct. The acceleration due to gravity is dependent on the rotation of the earth. Therefore the reason is incorrect.
The answer is Option (C): The assertion is correct but the reason is incorrect.

Note: The acceleration due to gravity will decrease as the height from the surface of the earth increases. The acceleration due to gravity decreases with depth also. At the centre of the earth, the acceleration due to gravity is zero. Hence we feel weightlessness at the centre of the earth.