A small grinding wheel is attached to the shaft of an electric motor that has a rated speed of 3600 rpm. When the power is turned off, the unit coasts to rest in 70 s. The grinding wheel and rotor have a combined weight of 6 lb and a combined radius of gyration of 2 in. Determine the average magnitude of the couple due to kinetic friction in the bearings of the motor.

The system is at rest with the spring unstretched when theta = 0. the 5.3 kg uniform slender bar is then given a slight clockwise nudge. The value of b is 0.45 m. (a) if the bar comes to momentary rest when theta = 58, determine the spring constant k. (b) for the value k = 65 N/m, find the magnitude of the angular velocity of th ebar when theta = 38 degrees.

The system is at rest with the spring unstretched when theta = 0. the 5.3 kg uniform slender bar is then given a slight clockwise nudge. The value of b is 0.45 m. (a) if the bar comes to momentary rest when the angle = 58, determine the spring constant k. (b) for the value k = 65 N/m, find the magnitude of the angular velocity of the bar when the angle = 38 degrees. a) k = 70.634 N/m

The slotted circular disk whose mass is 4.9 kg has a radius of gyration about O of 230 mm. The disk carries the four steel balls, each of mass 0.17 kg and located as shown, and rotates freely about a vertical axis through O with an angular speed of 164 rev/min. Each of the small balls is held in place by a latching device not shown. If the balls are released while the disk is rotating and come to rest relative to the disk at the outer ends of the slots, compute the new angular speed N of the disk. Also find the magnitude |AE| of the energy loss due to the impact of the balls with the ends of the slots. Neglect the diameter of the balls and discuss this approximation. 164 rev/min 145 mm 305 mm