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Unformatted text preview: hanna (brh687) hk 11 Opyrchal (11105) 1 This printout should have 14 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A bowling ball has a mass of 4 . 7 kg, a moment of inertia of 0 . 127088 kg m 2 , and a radius of . 26 m. It rolls along the lane without slipping at a linear speed of 3 . 7 m / s. What is the kinetic energy of the rolling ball? Correct answer: 45 . 0401 J. Explanation: Let : v = 3 . 7 m / s , r = 0 . 26 m , m = 4 . 7 kg , and I = 0 . 127088 kg m 2 . E = E rot + E kin = 1 2 I 2 + 1 2 mv 2 = 1 2 I v 2 r 2 + 1 2 mv 2 = 1 2 (0 . 127088 kg m 2 ) (3 . 7 m / s) 2 (0 . 26 m) 2 + 1 2 (4 . 7 kg)(3 . 7 m / s) 2 = 45 . 0401 J keywords: 002 10.0 points A solid 101 N ball with a radius of 0.490 m rolls 8.9 m down a ramp that is inclined at 25 with the horizontal. If the ball starts from rest at the top of the ramp, what is the angular speed of the ball at the bottom of the ramp? The acceleration of gravity is 9 . 81 m / s 2 . Correct answer: 14 . 7054 rad / s. Explanation: Let: F g = 101 N r = 0 . 490 m d = 8 . 9 m = 25 g = 9 . 81 m / s 2 By conservation of energy, U i = K trans,f + K rot,f = 1 2 mv 2 f + 1 2 I 2 mg d (sin ) = 1 2 m ( r f ) 2 + 1 2 parenleftbigg 2 5 mr 2 parenrightbigg 2 f = 1 2 mr 2 2 f + 1 5 mr 2 2 f = 7 10 mr 2 2 f 2 f = 10 7 gd (sin ) r 2 f = radicalbigg 10 gd (sin ) 7 r 2 = radicalBigg 10(9 . 81 m / s 2 )(8 . 9 m)(sin 24 . 6 ) 7(0 . 49 m) 2 = 14 . 7054 rad / s . keywords: /* If you use any of these, fix the comment symbols. 003 (part 1 of 2) 10.0 points A particle is located at the vector position vectorr = (2 . 5 m) + (3 . 7 m) and the force acting on it is vector F = (5 . 5 N) + (4 N) . What is the magnitude of the torque about the origin? Correct answer: 10 . 35 N m. Explanation: hanna (brh687) hk 11 Opyrchal (11105) 2 Basic Concept: vector = vectorr vector F Solution: Since neither position of the par ticle, nor the force acting on the particle have the zcomponents, the torque acting on the particle has only zcomponent: vector = [ x F y y F x ] k = [(2 . 5 m) (4 N) (3 . 7 m) (5 . 5 N)] k = [ 10 . 35 N m] k . 004 (part 2 of 2) 10.0 points What is the magnitude of the torque about the point having coordinates [ a, b ] = [(0 . 5 m) , (6 m)]?...
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This note was uploaded on 04/07/2012 for the course PHYSICS 121 taught by Professor James during the Spring '12 term at University of Texas at Austin.
 Spring '12
 James
 Physics, Inertia, Mass

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