Question

A body weighs 200 N on the surface of the earth. How much it weigh half way down to the centre of the earth ?

• A. $150N$
• B. $200N$
• C. $250N$
• D. $100N$

Answer 1

The correct option is D $100N$

Acceleration due to gravity at a depth d from surface of earth
$g^{\prime }=g(1-\frac{d}{R})$ ....(1)
Where g = acceleration due to gravity at earth's surface
Multiplying by mass 'm' on both sides of (1)
$⟹m{g}^{\prime }=mg(1-\frac{d}{R})Here,(d=\frac{R}{2})$
$=200(1-\frac{R}{2R})=\frac{200}{2}=100N$