# Why does the earth revolves* around the sun?

Jan 28, 2016

If it did not it will fall in to the sun.

#### Explanation:

There are two balancing forces acting on earth when it revolves around the sun. [Source:mathworks.com]

Gravitational force of attraction.
Law of Universal Gravity states that every body in this universe attracts every other body with a force which is called force of gravity. The force

${F}_{G} = G \frac{{M}_{1.} {M}_{2}}{r} ^ 2$

Where ${M}_{1} \mathmr{and} {M}_{2}$ are mass of two interacting bodies, $r$ is the distance between the two and $G$ a constant.

It has the value $6.67408 \times {10}^{-} 11 {m}^{3} k {g}^{-} 1 {s}^{-} 2$
In our case, one is the sun and other earth.

Centrifugal force.
Centrifugal force is a 'fictitious' force that appears to act on all rotating objects and is directed away from the axis of rotation.
It is given by the expression

${F}_{c e n t r i f u g a l} = m r {\omega}^{2}$

where $m$ is the mass of rotating object, $r$ the radius of circle of rotation and $\omega$ its angular velocity.

These two forces balance each other and keep the sun-earth system in equilibrium.

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*in the question 'revolves' is preferred word as earth 'rotates' around its axis.