Question

Problem 7.46 - enhanced - with feedback a 200 g , 25-cm-diameter plastic disk is spun on an axle through its center by an electric motor. you may want to review ( pages 211 - 213) . part a what torque must the motor supply to take the disk from 0 to 2000 rpm in 4.6 s ?

Answer 1

Torque = I * α I = ½ * m * r^2 = ½ * 0.2 * 0.125^2 = 0.0015625 As the disk rotates one time, it rotates an angle of 2 π radians. Total angle = 1600 * 2 π = 3200 * π One minute is 60 seconds. To determine its initial angular velocity, divide this angle by 60. ω = 53⅓ * π This is approximately 167.55 rad/s. To determine the angular acceleration, divide by 4.1 seconds. α = 53⅓ * π ÷ 4.1 This is approximately 4.09 rad/s^2 Torque = 0.0015625 * (53⅓ * π ÷ 4.1) This is approximately 0.0639 N * m. electron1 · 2 years ago