Question

(b) What is the acceleration of gravity on the surface (or outer limit) of Neptune? The mass of Neptune is 1.02 1026 kg and its radius is 2.48 107 m.

m/s^2

Answer 1

To find the magnitude of the acceleration of gravity on the surface of a body with a big mass against any mass on it's surface the acceleration can be written as follows:

$g= \frac{G\cdot M}{r^{2}}$

We must also know that gravity tends to attract bodies so the gravitational force point to the center of the planet, in this case, Neptune.

Substituting values we have:

$g= \frac{6.67384\cdot 10^{-11}Nm^{2}/kg^{2}\cdot 1.02\cdot 10^{26}kg}{(2.48\cdot 10^{7})^{2}}=11.06 m/s^{2}$

This acceleration is bigger than the 9.81 m/s2 on earth. This also means that your weight would be higher on Neptune than on earth since this force is proportional to the acceleration of gravity