Q89 / 160 · JIPMER 2014 · Physics
Change in acceleration due to gravity is same upto a height $h$ from each other the earth surface and below depth $x$, then relation between $x$ and $h$ is ( $h$ and $x\lt\lt \lt R_e$ )
- A$x=h$
- Correct answerB$x=2 h$
- C$x=\frac{h}{2}$
- D$x=h^2$
Solution
Variation in $g$ at a height $h$ from the earth surface $g^{\prime}=g\left(1-\frac{2 h}{R_e}\right)$
Variation in $g$ at a depth $x$ below the earth surface $g^{\prime \prime}=g\left(1-\frac{x}{R_b}\right)$
But variations are same
$\therefore \quad g\left(1-\frac{2 h}{R_\theta}\right)=g\left(1-\frac{x}{R_\theta}\right)$
$\therefore \quad x=2 h$
Hence, the correct answer is option: 'B'.