A figure skater presses off the ice to begin spinning with her arms close to her...

A figure skater presses off the ice to begin spinning with her arms close to her body. After completing 2 turns in 0.8 seconds she moves her arms further away from her body, what will her new angular velocity be?

a. <16.6 rad/s

B. 18 rad/s

C. 20 rad/s

D. 24 rad/s

Solutions

Expert Solution

The skater turned 2 turns in 0.8 seconds

2 turns means 2* = radians.

So, the angular velocity initially is

Now, the angular momentum is given by

Where r is the radius of rotation.

When the person stretches the arms out, the radius r changes.

But according to the law of conservation of angular momentum,

L will remain the same.

So, the new angular velocity will be

Since r2 > r1

The new angular frequency will be less than 15.7 rad/s

So, option A is correct

Note: There must be some error is the values provided. The answer a should have been <15.7 exactly or the value of time is different. However, the steps and the answer remains the same

genius_generous answered 1 year ago

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