Question

4. Suppose we want to calculate the moment of inertia of a 67 kg skater, relative to a vertical axis through their center of mass. a. First calculate the moment of inertia (in kg.m2) when the skater has their arms pulled inward by assuming they are cylinder of radius 0.125 m. b. Now calculate the moment of inertia of the skater (in kg.m2) with their arms extended by assuming that each arm is 5% of the mass of their body. Assume the body is a cylinder of the same size, and the arms are 0.975 m long rods extending straight out from the center of their body being rotated at the ends.

Answer 1

Answere 100 @ for solid cyünder & I = 12mp2 I = 4 x 6 7X (0.125)2 = 0.52 kg.m2 6 length of arm=0.975 m. mass of arm - 67X5 = 3.35 kg each now mass of cylindrical body = 67- (2X3.35) = 60.3 kg so moment of Inertia = 1 mR2 + 2 (m'12 ) 1'4x60.3 x(0.125)+2(3-35x(0.9745)2) - l'= 0.47+ 1.90 (1 = 2.37 leg. m2 Ans. -

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