# How did we calculate the mass of Earth?

## How did we calculate the mass of Earth?

We start by determining the mass of the Earth. Because we know the radius of the Earth, we can use the Law of Universal Gravitation to calculate the mass of the Earth in terms of the gravitational force on an object (its weight) at the Earth’s surface, using the radius of the Earth as the distance.

### What is the big G in physics?

The constant of proportionality, G, is the gravitational constant. Colloquially, the gravitational constant is also called “Big G”, distinct from “small g” (g), which is the local gravitational field of Earth (equivalent to the free-fall acceleration).

Is value of g same every where?

The value of g at all place is not the same, it varies. The value of g is more at the poles and less at the equator. Hence on the basis of altitude the value of g changes.

How would the value of G and G be affected if the mass of Earth becomes four times?

G is a universal constant, not related to Earth, and would not charge with the mass of Earth. g on the other hand is proportional to the mass of Earth, so if the Earth’s mass were to quadruple with unaltered radius, g would also quadruple.

## What change will be produced in G if the mass of Earth is doubled?

If the mass of both of the objects is doubled, then the force of gravity between them is quadrupled; and so on. Since gravitational force is inversely proportional to the square of the separation distance between the two interacting objects, more separation distance will result in weaker gravitational forces.