Question

The mass of a certain planet P is one-hundredth that of the earth while the radius is one quarter of the earth's radius. If the acceleration due to gravity on the earth is 10m/s2,what is the value of P?

Answer 1

The acceleration due to gravity

$$g=G\frac{M}{R^2}$$

So

$$\frac{g_P}{g_E}=\frac{M_P}{M_E}\times \frac{R_E^2}{R_P^2}$$

$$\frac{g_P}{10}=\frac{1}{100}\times 16$$

$$g_P=1.6\:\rm m/s^2$$