Question

The earth exerts a gravitational force of 1,9 x 1020 N on the moon. The mass of the moon is 7,4 x 1022 kg and its radius is 1,74 x 106 m.

An astronomer that weighs 20 kg on earth, lands on the moon. What would his mass be on the moon?

Answer 1

$m=20 \; kg \\ g = 9.8 \; m/s^2$

weight of object on Earth $= mg = 20 \times 9.8 = 196 \;N$

Weight of object on Moon $= \frac{1}{6} \times$ (weight of object on Earth)

$= \frac{1}{6} \times 196 \\ = 32.66 \;N$