Posted by **Tarren** on Thursday, December 2, 2010 at 1:17pm.

A skater spinning with angular speed of 1.5 rad/s draws in her outstretched arms thereby reducing her moment of inertia by a factor a 3.

a) Find her angular speed.

b)What is the ratio of her final angular momentum to her initial angular momentum?

c)Did her mechanical energy change? (Yes but why?)

- Physics -
**Tarren**, Thursday, December 2, 2010 at 1:19pm
I forgot to add one more part.

d) Determine the ratio of her final kinetic energy to her initial kinetic energy.

- Physics -
**drwls**, Thursday, December 2, 2010 at 2:26pm
I*w stays the same due to the requirement for angular momentum conservation.

If I is cut in half, w must double.

KE is (1/2)I*w^2 = (1/2)(I*w)^2/I

Since I drops by half while I*w is constant, the kinetic energy must also double.

The extra KE comes from work done by the skater pulling in her arms. There is a lot of centrifugal resistance.

## Answer this Question

## Related Questions

physics - A skater spinning with angular speed of 1.5 rad/s draws in her ...

ice skater world problem - A skater spins with an angular speed of 12.4 rad/s ...

physics - An ice skater has a moment of inertia of 2.3 kg * m^2 when his arms ...

Physics - A figure skater is spinning with an initial angular speed of 6.9rad/s...

Physics - A woman stands at the center of a platform. The woman and the platform...

Physics - A person on a rotating stool with arms stretched out rotates at an ...

physics - An ice skater spins about a vertical axis at an angular speed of 15 ...

Physics - The outstretched hands and arms of a figure skater preparing for a ...

physics - The outstretched hands and arms of a figure skater preparing for a ...

physics - (a) Calculate the angular momentum of an ice skater spinning at 6.00 ...