Question

The height of the point vertically above the earth’s surface, at which acceleration due to gravity becomes 1% of its value at the surface is (Radius of the earth = R)

• A. 8 R
• B. 9 R
• C. 10 R
• D. 20 R

Answer 1

Answer: (B)

9 R

Answer 2

$\frac { g ^ { \prime } } { g } = \left( \frac { R } { R + h } \right) ^ { 2 } \Rightarrow \frac { 1 } { 100 } = \left( \frac { R } { R + h } \right) ^ { 2 } \Rightarrow h = 9 R$