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Question :
71. An ice skater spins at 2.5 rev/s when his : 2102164

71. An ice skater spins at 2.5 rev/s when his arms are extended. He draws his arms in and spins at 6.0 rev/s. By what factor does his moment of inertia change in the process?

A. 2.4

B. 1.0

C. 0.42

D. 0.12

72. A figure skater on ice with arms extended, spins at a rate of 2.5 rev/s. After he draws his arms in, he spins at 6.0 rev/s. By what factor does the skater's kinetic energy change when he draws his arms in?

A. 2.4

B. 1.0

C. 0.42

D. 0.12

73. A turntable has a moment of inertia of 3.00 ´ 10^{-2} kg?m^{2} and spins freely on a frictionless bearing at 25.0 rev/min. A 0.300-kg ball of putty is dropped vertically onto the turntable and sticks at a point 0.100 m from the center. What is the new rate of rotation of the system?

A. 40.8 rev/min

B. 22.7 rev/min

C. 33.3 rev/min

D. 27.2 rev/min

74. A turntable has a moment of inertia of 3.00 ´ 10^{-2} kg?m^{2} and spins freely on a frictionless bearing at 25.0 rev/min. A 0.300-kg ball of putty is dropped vertically on the turntable and sticks at a point 0.100 m from the center. By what factor does the angular momentum of the system change after the putty is dropped onto the turntable?

A. 1.22

B. 1.00 (no change)

C. 0.820

D. 1.50

75. A turntable has a moment of inertia of 3.0 ´ 10^{-2} kg?m^{2} and spins freely on a frictionless bearing at 25 rev/min. A 0.30-kg ball of putty is dropped vertically on the turntable and sticks at a point 0.10 m from the center. By what factor does the kinetic energy of the system change after the putty is dropped onto the turntable?

A. 0.91

B. 1.0

C. 0.82

D. 1.5