Mass of the Rigidbody.
The mass is given in arbitrary units, but the basic physical principles of mass apply. Newton's classic equation `force = mass x acceleration`, demonstrates that the larger an object's mass, the more force it requires to accelerate it to a given velocity. Mass also affects momentum, which is significant during collisions; an object with large mass will be moved less by a collision than an object with lower mass.
The mass can also be automatically calculated when useAutoMass is true. In this case, you cannot set the mass property directly.
See Also: useAutoMass.