Question

A typical adult human has a mass of about 70 𝑘𝑔. (a) What force does a full moon exert on such a human when it is directly overhead with its center 378,000 𝑘𝑚 away? (b) Compare this force with the force exerted on the human by the earth.

Answer 1

(a) The force is

$$F=GMm/R^2=2.4·10^{-3}\text{ N}.$$

(b) On the Earth, it is

$$F=mg=686\text{ kg}.$$