Centre of Mass

The centre of mass is an imaginary point.  It is the point at which the body’s weight can be considered to act. It represents the centre of all the mass and the body will balance and rotate around this imaginary point.

The position of the centre of mass will depend on the mass itself.  For example a football’s centre of mass will always be in the same spot, providing the ball was solid and not deflated.  Half the balls mass would be to the left and to the right, half will be above and half below the CoM, half is in front and half is behind the CoM.

Its harder to work out where the centre of mass is located when you are talking about a human body as we need to
consider not only the torso, but the head, arms and legs and the composition  of the body itself.The mass is distributed across the body in an uneven fashion, and because our body parts can move in various directions
the centre of mass will move according to the position of the body and its limbs.

In the human body standing at rest with the arms by the sides the centre of mass  It would be in the middle between your tummy button and the small of your back in most people.  You would need to consider the shape and weight of
the body in question.