Question

What will be the formula of mass of the earth in terms of $g, R$ and $G$ ?

• A. $G \frac{R}{g}$
• B. $g \frac{R^2}{G}$
• C. $g^2\frac{R}{g}$
• D. $G \frac{g}{R}$

Answer 1

Answer: (B)

The gravitational force $(F)=\frac{G M m}{R^{2}}$ and $F=m g$.
Equating both the values of gravitational force, $\frac{G M m}{R^{2}}=m g$
or $M=g \frac{R^{2}}{G}$,
where $M$ is the mass of the earth.