9.0

176 RIGID BODIES
DYNAMICS
DYNAMICS
RIGID BODIES 177
Rotational Mass
This parameter enables you to ne-tune the rotational behavior of the rigid body.
The value is specied as a percentage of the Total Mass value. The higher this Total
Mass value then the greater the force that will be required to change the rotation
of the rigid body.
Center
These three input boxes dene the X,Y,Z position of the mass centre in relation to the
origin. It is an offset. To move the centre of mass, enter the desired offset.
Each rigid body has a mass centre. By default, the mass centre will be in the same
position as the rigid body’s origin. The Center parameters enable you to change the
position of the centre of mass, which is displayed in the viewport as a yellow cross.
The mass centres of various
objects.
If a force is exerted on the centre of mass, the rigid body will experience linear
acceleration only in the direction of the force. If the force is instead exerted on a
point away from the centre of mass, such as may happen during a collision, the rigid
body will experience angular as well as linear acceleration, which will cause it to
rotate as well as move.
The centre of mass is also used to determine whether the rigid body is inside a eld.
The force will be exerted only if the centre of mass is inside the eld.
Lastly, a rigid body attached to an angular spring or used with a constraint will rotate
about its centre of mass.