F = G m1 m2 / r2
This equation shows the force a body applies on another body through gravity and weight. G is the universal gravity constant (roughly 6.67x10-11 Nm2/kg2).
This simulator allows you to see how bodies interact in space. Drag the spawner around to change the start position. Click 'spawn' to create a new body. In this case, you are spawning the equivelent of half a Earth-like moon.
Time is sped up in order to make this an interesting simulator. (The distances are so huge that they would move a pixel a minute, even though they are travelling at many kilometres per second.)
This simulator follows relativity: bodies gain mass as they go faster.
m = m0 / ( 1 - V2 / C2)
The mass tends towards infinity as the velocity approaches the speed of light.
Ek = ½ m v2
The required energy tends towards infinity.