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 ( Ibar = 1 12 mℓ2 where ℓ is the length of the bar ). When the skater's hands and arms are brought in and wrapped around their body to execute the spin, the hands and arms can be considered a thin-walled hollow cylinder. The hands and arms have a combined mass 10 kg. When outstretched, they span 1.9 m. When wrapped, they form a cylinder of radius 35 cm. The moment of inertia about the rotation axis of the remainder of the body is constant and equal to 0.3 kg·m2. If the original angular speed is 0.3 rev/s, what is the final angular speed?

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 (Ibar = 5 ml2 where l is the length of the bar). When the skater's hands and arms are brought in and wrapped around their body to execute the spin, the hands and arms can be 12 considered a thin-walled hollow cylinder. The hands and arms have a combined mass 10 kg. When outstretched, they span 1.9 m. When wrapped, they form a cylinder of radius 35 cm. The moment of inertia about the rotation axis of the remainder of the body is constant and equal to 0.3 kg.m2. If the original angular speed is 0.3 rev/s, what is the final angular speed? 0.2612 rev/s

Answer 1

span length (L) = 1.9m Dnitial angular speed (Wi) = 0.3 rev/sec radius (i = 0.35m mass (m) = lokg Moment of inclia of body (IG) = 0 .3 Kg m2 Now, Total Initial moment of Enerlia (I) = 0.3 + 1 m ² = 0.3 + 1x10x1.92 D = 3.30834 kg-m2 final total Moment of Inestia ia (If) = Tel. 0.3+ mrz = 0.3 + 10x 0.352 = 1.525 kg m 2 Since external force, there fore there is no conserved. angular momentum will be se Ii Wi - If Wf 303 0834 x • 3 = 1.525xWf or wf = 0.6508 rev/see * * if you Please doubt LIKE. please ask. THANK You.