The outstretched hands and arms of a figure skater preparing for a spin can be c
ID: 2264780 • Letter: T
Question
The outstretched hands and arms of a figure skater preparing for a spin can be considered a slender rod pivoting about an axis through its center. When his hands and arms are brought in and wrapped around his body to execute the spin, the hands and arms can be considered a thin-walled hollow cylinder. His hands and arms have a combined mass 9.0 kg. When outstretched, they span 1.8 m. when wrapped they form a cylinder of radius 26 cm. The moment of inertia about the rotation axis of the remainder of his body is constant and equal to .40 kg*m^2. If his original angular speed is 0.30 rev/sec, what is his final angular speed?
Explanation / Answer
initial moment of inertia of body
I1 = 0.4 + 9*1.8^2/12 = 2.83 kg.m^2
final moment of inertai a body
I2 = 0.4 + 9*0.26^2 = 1.0084 kg.m^2
here initial angular momentum = final angular momentum
I1*w1 = I2*w2
2.83*0.3 = 1.0084*w2
==> w2 = 2.83*0.3/1.0084
==> w2 = 0.8418 rev/s or 5.287 rad/s
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.