A 45 {\ m kg figure skater is spinning on the toes of her skates at 0.60 rm rev/

Question

A 45 { m kg figure skater is spinning on the toes of her skates at 0.60 rm rev/s). Her arms are outstretched as far as they will go. In this orientation, the skater can be modeled as a cylindrical torso (40 { m kg) 20 m cm average diameter, 160 ( m cm tall) plus two rod-like arms (2.5 m kg each, 71 m cm) long) attached to the outside of the torso. The skater then raises her arms straight above her head, where she appears to be a 45 m kg, 20- cm 200- m cm- tall cylinder. What is her new rotation frequency, in revolutions per second? Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

R=D/2 =0.1 m

Initial Moment of inertia

I1=(1/2)*M*R2 +2*[(1/12)*m*L2+m*(R+L/2)^2]

I1=(1/2)*40*0.12+2[(1/12)*2.5*0.712 +2.5*(0.1+0.71/2)2]

I1=1.445 Kg-m2

Final Moment of inertai

I2=(1/2)*M*R2

I2=(1/2)*45*0.1^2 =0.225 Kg-m^2

By conservation of angular momentum

I1*W1=I2*W2

1.445*0.6=0.225*W2

W2=3.85 rev/s

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.