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Question :
31. A disk has a moment of inertia of 3.0 : 2102172

31. A disk has a moment of inertia of 3.0 ´ 10^{-4} kg?m^{2} and rotates with an angular speed of 3.5 rad/sec. What net torque must be applied to bring it to rest within 3 s?

A. 4.5 ´ 10^{-3} N?m

B. 7.5 ´ 10^{-4} N?m

C. 3.5 ´ 10^{-4} N?m

D. 5.0 ´ 10^{-4} N?m

32. The Earth moves about the Sun in an elliptical orbit. As the Earth moves closer to the Sun, which of the following best describes the Earth-Sun system's moment of inertia?

A. decreases

B. increases

C. remains constant

D. none of the above choices are valid

33. A bowling ball has a mass of 7.0 kg, a moment of inertia of 2.8 ´ 10^{-2} kg?m^{2} and a radius of 0.10 m. If it rolls down the lane without slipping at a linear speed of 4.0 m/s, what is its angular speed?

A. 0.80 rad/s

B. 10 rad/s

C. 0.050 rad/s

D. 40 rad/s

34. A baseball pitcher, loosening up his arm before a game, tosses a 0.15-kg ball using only the rotation of his forearm, 0.32 m in length, to accelerate the ball. If the ball starts at rest and is released with a speed of 12 m/s in a time of 0.40 s, what is the average angular acceleration of the arm and ball?

A. 0.067 rad/s^{2}

B. 94 rad/s^{2}

C. 15 rad/s^{2}

D. 37 rad/s^{2}

35. A baseball pitcher loosens up his pitching arm. He tosses a 0.15-kg ball using only the rotation of his forearm, 0.32 m in length, to accelerate the ball. What is the moment of inertia of the ball alone as it moves in a circular arc with a radius of 0.32 m?

A. 1.5 ´ 10^{-2} kg?m^{2}

B. 16 ´ 10^{-2} kg?m^{2}

C. 4.0 ´ 10^{-2} kg?m^{2}

D. 7.6 ´ 10^{-2 }kg?m^{2}