Centre of gravity

The centre of gravity of an object is basically where all its weight acts, or where all the mass is acting.

Moments around the centre of gravity

The moments need to add so that the resultant moment is zero.

Basically, the clockwise moments need to equal the anticlockwise moments.

Because both moments must be equal, we can describe two objects of W weight and d distance from the centre of gravity:

W_1d_1=W_2d_2

Question	Answer
Centre of gravity	The point where all the weight (or mass) of an object is considered to act.
What must be true when moments are balanced around the centre of gravity?	The resultant moment must be zero, meaning clockwise moments equal anticlockwise moments.
What is the formula for two weights balancing around the centre of gravity?	W_1d_1=W_2d_2, where W is weight and d is distance from the centre of gravity.