Question

Assuming that the Earth is a sphere of uniform mass density, find the percentage decrease in the weight of a body when taken to the end of a tunnel 32 Km below the surface of Earth. Radius of Earth = 6400 Km

• A. 0.6
• B. 0.5
• C. 0.7
• D. 0.8

Answer 1

The correct option is B 0.5

$g^{\prime }=g(1-\frac{d}{R})$

$⟹\Delta g=g\frac{d}{R}$.

Percentage decrease in weight is $\frac{m\Delta g}{mg}\times 100$

$=\frac{32}{6400}\times 100$

$=0.5\%$