Fig. 32.
Why will a ball remain in any position when placed on the earth?
Because its centre of gravity is always the same distance from the earth, whatever may be its position.
When will a body change its position if left unsupported?
A body will change its position whenever by so doing its centre of gravity will be lowered.
When may a body be readily moved about?
When its centre of gravity always remains at the same distance from the earth while being moved.
Why is a round body, like a ball, easily rolled about the floor?
Because its centre of gravity remains at the same distance from the floor.
When is the position of a body difficult to change?