1.) A Olympic spinning ice skater on extremely smooth ice is able to control the
ID: 1282160 • Letter: 1
Question
1.) A Olympic spinning ice skater on extremely smooth ice is able to control the rate at which she rotates by pulling in her arms. Which of the folowing statements are true about the skater during the process?
a.) Her angular momentum remains constant.
b.) Her momentum of intertia remains constant.
c. ) Her kinetic energy remains constant.
d.) She is subject to a constant non-zero torque.
2.) Imaging sitting on a freely spinning class chair that has no friction it its axle. When you extend your arms,
a.) your moment of inertia decreases and your angular speed increases
b.) your moment of inertia decreases and your angular speed decreases.
c.) your moment of inertia increases and your angular speed increases.
d.) your moment of inertia increases and your angular speed decreases.
e.) your moment of inertia inreases and your angular speed remains the same.
Please give answer and explains,thanks!
Explanation / Answer
a.) Her angular momentum remains constant.
For an object to remain in equilibrium, two conditions must be satisfied - both the net force and the net torque must be equal to zero.
SF = 0
St = 0
Hence
a.) Her angular momentum remains constant.
Part b
As momemt of inertia
I=m r^2
as a person open his arms, r increases so I increases and if momentum of a system is constant, then the moment of inertia increases, the angular velocity must decrease so
d.) your moment of inertia increases and your angular speed decreases.
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