57 556
Assignments Done
98,9%
Successfully Done
In February 2018
Your physics homework can be a real challenge, and the due date can be really close — feel free to use our assistance and get the desired result.
Be sure that math assignments completed by our experts will be error-free and done according to your instructions specified in the submitted order form.
Our experts will gladly share their knowledge and help you with programming homework. Keep up with the world’s newest programming trends.

Answer on Mechanics | Relativity Question for Bhawana

Question #7918
An ice skater spins about a vertical axis at an angular speed of 15 rad s−1 when her arms are
outstretched. She then quickly pulls her arms into her sides in a very small time interval so
that the frictional forces due to ice are negligible. Her initial moment of inertia about the
axis of rotation is 1.72 kg m2 and her final moment of inertia is 0.61 kg m2. What is the
change in her angular speed? What is the change in her kinetic energy? Explain this change
in kinetic energy.
Expert's answer
Let moments of inertia be I1 and I2 and angular speeds be w1 and w2

Angular momentum is conserved

I1 x w1 = I2 x w2

w2 = 1.72 x 15 / 0.61

= 43 rad/s (approximately)

Therefore change in angular speed = 43 - 15 = 28rad/s increase

Change in KE = ( I2 x w2^2 - I1 x w1^2 ) / 2

=( 0.61 x 43^2 - 1.72 x 15^2) / 2

= 363.45J

That is KE has actually increased .This is because of external work done by the skater while pulling her hands closer

Need a fast expert's response?

Submit order

and get a quick answer at the best price

for any assignment or question with DETAILED EXPLANATIONS!

Comments

No comments. Be first!

Leave a comment

Ask Your question