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A cable passes over a pulley. Because the cable grips the pulley and the pulley

ID: 1742887 • Letter: A

Question

A cable passes over a pulley. Because the cable grips the pulley and the pulley has non- zero mass, the tension in the cable is not the same on opposite sides of the pulley. The force on one side is 190 N, and the force on the other side is 78 N. Assuming that the pulley is a uniform disk of mass 0.85 kg and radius 1.195 m, determine the magnitude of its angular acceleration. An- swer in units of rad/s2. A cable passes over a pulley. Because the cable grips the pulley and the pulley has non- zero mass, the tension in the cable is not the same on opposite sides of the pulley. The force on one side is 190 N, and the force on the other side is 78 N. Assuming that the pulley is a uniform disk of mass 0.85 kg and radius 1.195 m, determine the magnitude of its angular acceleration. An- swer in units of rad/s2.

Explanation / Answer

        Given that theforces are F1 = 190 N and F2 = 78 N         Mass of the diskis M = 0.85 kg         Radius of the diskis R = 1.195 m ----------------------------------------------------------------------------------          The torque onthe pully is                                     = F1*R - F2*R                                I =  F1*R - F2*R                                  = ( F1*R - F2*R ) / I                    But the moment of inertia of the disk is I =(1/2)MR2                                  = ( F1*R - F2*R ) / (1/2)MR2                                     =2( F1 - F2 ) / MR                                       =----------rad/s2                                            =2( F1 - F2 ) / MR                                       =----------rad/s2