Question

What bodily position would result in the greatest moment of inertia, relative to the frontal axis, for a gymnast who is rotating in the sagittal plane?

Answer 1

Moment of inertia is proportional to mass and square of distance from axis.

In this case mass will remain fixed so distance from axis can be changed.

For the greatest moment of inertia the mass distribution should be far from the axis of rotation (here frontal axis).

i.e. bodily position should be such that the mass is distributed far from the axis. So gymnast should stretch away from axis.

Sagittal plane osivertical plane which devide the body in left and right.

And frontal axis runs from left to right through centre of body.

So to maximaze the moment of inertia the gymnast should stretch his body length wise. i.e. the required position will be his aximunm height streaching hands and legs align with the body making completly straight.

Answer: straight stand.

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