Question

A man weighs $600N$ on the equator, but when he moves to the pole he finds a slight increase in his weight. This is because:

• A. Radius of the Earth is less at poles.
• B. Radius of the Earth is more at poles.
• C. The mass of the Earth increases at poles.
• D. Newton's law of gravitation is not applicable at the poles.

Answer 1

The correct option is A

Radius of the Earth is less at poles.

We know that, acceleration due to gravity,
$g=\frac{GM}{R^2}$​
Weight is the force due to gravity i.e., $mg$.
Since the Earth is not a perfect sphere, its radius ${}^{\prime }{R}^{\prime }$ is smaller at poles than at equators. The value of acceleration due to gravity ${}^{\prime }{g}^{\prime }$ increases at poles as ${}^{\prime }{g}^{\prime }$ is inversely proportional to ${}^{\prime }{R}^{\prime }$. Hence, the weight of the body also increases at poles.