Editing Gravity

'''Gravity''' is one of the [[four fundamental forces]]. It is the weakest of the four forces, yet one of the most easily observed. It causes a mutual attraction between two bodies by virtue of their [[mass]]es. Gravitational force is believed to be caused by the exchange of yet to be discovered particles called ''gravitons''. On earth, the [[force]] of gravity on an object is equal to 9.8 N/kg; therefore, all falling objects [[acceleration|accelerate]] at 9.8 m/s<sup>2</sup>.
According to [[Newton's Law of gravitation]]:
Given masses ''m<sub>1</sub>'' and ''m<sub>2</sub>'' at a distance of ''r'', the [[force]] between them is equal to

:<math>F= \frac{G m_1 m_2}{r^2}</math>

''G'' is the gravitaional constant, equal to 6.673×10−11 N·(m/kg)<sup>2</sup>.

The same two masses will have a [[potential energy]] of

:<math>E_p = - \frac{G m_1 m_2}{r}</math>

with respect to infinity; in other words, this is the amount of [[work]] required to push one of the objects infinitely far away from the other. This gives a formulation for escape velocity, or the velocity needed to escape an object's gravitational pull:

:<math>\frac{G M m}{r} = \frac{1}{2} m v^2</math>
:<math>\frac{G M}{r} = \frac{1}{2} v^2</math>
:<math>v_e = \sqrt{ 2 \frac{G M}{r} }</math>

For earth, this equals approximately 11186.1 m / s.

Gravity is a central force i.e. it acts along the line joining the centres of the two bodies. It is a [[conservative force]] and thus the work done by the gravity on an object is path independent.

==References==
<references />

[[Category:Gravitation]]
[[Category:Dynamics]]
[[Category:Needs References]]