Question

Mass of moon is $7.34 \times 10^{22}kg.$ If the acceleration due to gravity on the moon is 1.4m/s², the radius of the moon is $(G = 6.667 \times 10^{- 11}Nm^{2}/kg^{2})$

• A. $0.56 \times 10^{4}m$
• B. $1.87 \times 10^{6}m$
• C. $1.92 \times 10^{6}m$
• D. $1.01 \times 10^{8}m$

Answer 1

Answer: (B)

$1.87 \times 10^{6}m$

Answer 2

We know $g = \frac{GM}{R^{2}}$

$\therefore R = \sqrt{\frac{GM}{g}} = \sqrt{\frac{6.67 \times 10^{- 11} \times 7.34 \times 10^{22}}{1.4}} = 1.87 \times 10^{6}m$.