# Physics ang. momentum

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A diver can reduce her moment of inertia by a factor of about 3.5 when changing from the straight position to the tuck position. If she makes 2.0 rotations in 1.5s when in the tuck position, what is the percent change in her kinetic energy as she changes to the straight position??

Please explain to me how to get this problem step by step.

• Physics ang. momentum -

The kinetic energy can increase because of muscular work done going into the tuck position.

Remember that I * w remains constant. Angular momentum conservation is not violated.

If the momen t of inertia I decreases by a factor of 3.5,then the angular frequency w increases by a factor 3.5, and the kinetic energy, (1/2)I w^2, increases by a factor
(1/3.5)*(3.5)^2 = 3.5

The percent change in KE is therefore +250%

• Physics ang. momentum -

How is it +250%?

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