A body weighs 200 N on the surface of the earth. How much will it weigh half way down to the centre of the earth ?
Answer & explanation
Correct answer: option 1
Acceleration due to gravity at a depth d from surface of earth
g′ = 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)
mg′ = mg(1 - \(\frac{d}{R}\)) (d= \(\frac{R}{2}\))
= 200(1 - \(\frac{R}{2R}\)) = \(\frac{200}{2}\)
= 100N