While we usually think of the gravity due to planets when we reside on their surface or orbit around them, it is intriguing to consider the role that gravitation plays inside a large body.
Newton's law of universal gravitation states that all bodies having mass emit a gravitational field and thereby attract all other masses to them. The magnitude of the attractive force (which, by Newton's third law, acts on both bodies) is governed by the mass of each body, as well as their proximity to one another. The force is stronger for more massive bodies, and increases as the gap between them reduces. In equation form, the magnitude of the gravitational force, Fg (in Newtons), that acts on both bodies is given by
Fg = GM1M2/r2 (refer to figure below)
Here, G is known as the universal gravitational constant (6.673 × 10-11 m3/kg s2), M1 and M2 are the masses of each of the bodies (kg), and r is the distance that separates them (m).
