Question

One can easily weighs the earth by calculating the mass of earth using the formula (in usual notation)

• A. $\frac{G}{g}R_{E}^{2}$
• B. $\frac{g}{G}R_{E}^{2}$
• C. $\frac{g}{G}R_E$
• D. $\frac{G}{g}R_{E}^{3}$

Answer 1

Answer: (B)

$\frac{g}{G}R_{E}^{2}$

Answer 2

Force, $F =G \frac{M_{E} m}{R_{E}^{2}}$ $m g =G \frac{M_{E} m}{R_{E}^{2}}$ $(\therefore F=m g)$ $g =\frac{G M_{E}}{R_{E}^{2}}$ or $M_{E}=\frac{g R_{E}^{2}}{G}$