# Gravity

## Fact File

Here are some important facts about gravity:
 Using scientific language Which translate to... Gravity is the experience of two particles mutually attracting each other along the line joining them. Imagine yourself deep in space and you are standing next to a brick. When you are running in a marathon, you are running in a particular direction, but gravity has no particular direction, but along the path joining you and that brick. Spherically symmetric objects interact gravitationally as if their mass were located at their centers. An example of a spherically symmetric object is the Earth.  Earth attracts as if it's mass were located at the centre of Earth. It is gravity which causes the centripetal acceleration when a satellite moves in a circular orbit. Gravity is what allows a satellite to move in a circular orbit around earth. For a particular radius of circular orbit there is only one possible speed for a stable satellite orbit. If a satellite wants to orbit 2,000km above Earth, there is only one speed at which it can stably orbit. If you increase either mass, the Force will increase.  If you decrease either mass, the Force will decrease. If you increase the radius, the Force will decrease.  If you decrease the radius, the Force will increase. Click here to find more information about this formula, as this is used in combination with Newton's law of universal gravitation. 