The height of any point \( P \) above the surface of earth is equal to diameter of earth. The value of acceleration due to gravity at point \( P \) will be: (Given \( g \) = acceleration due to gravity at the surface of earth).
\( \frac{g}{2} \)
\( \frac{g}{4} \)
\( \frac{g}{3} \)
\( \frac{g}{9} \)