A flywheel of mass 140 kg with a radius of gyration of 0.1 m is accelerated uniformly from 200 rpm to 1800 rpm. This takes 14 s. Ignoring friction, find the constant torque T needed.
A flywheel is a uniform solid disc of mass 30 kg and radius 0.7 m. It spins at 1800 rpm. Find its kinetic energy Ek in kJ.
A 2 kg block hangs from a light cord wrapped around a pulley, a uniform solid disc of mass 5 kg and radius 0.3 m that turns on a frictionless horizontal axle. The block is released from rest. Use g = 9.81 m/s². Find the angular acceleration α of the pulley.
A shaft transmits 24.5 kW at 1000 rpm. Find the torque T in the shaft.
A hollow sphere rolls without slipping down a slope inclined at 20° to the horizontal. Use g = 9.81 m/s². Find the acceleration a of its centre.
A person stands on a frictionless turntable and holds a 5 kg dumbbell in each hand, 0.8 m from the axis. The person and turntable alone have a moment of inertia of 2.5 kg·m² about the axis. They turn at 35 rpm, then pull the dumbbells in to 0.35 m from the axis. Treat the dumbbells as point masses. Find the new speed n2 in rpm.
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