A flywheel of mass 20 kg with a radius of gyration of 0.15 m is accelerated uniformly from 600 rpm to 2300 rpm. The driving torque is a constant 8 N·m and friction can be ignored. How long t does this take?
A uniform slender rod of mass 2.5 kg and length 2 m rotates about an axis O perpendicular to the rod, 0.4 m from its centre G. Find its mass moment of inertia IO about that axis.
A motor brings a flywheel with a moment of inertia of 12 kg·m² from rest up to 2000 rpm in 41 s. Ignoring losses, find the average power Pavg it delivers, in kW.
A 3 kg block hangs from a light cord wrapped around a pulley, a uniform solid disc of mass 11.5 kg and radius 0.15 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 person stands on a frictionless turntable and holds a 4 kg dumbbell in each hand, 0.8 m from the axis. The person and turntable alone have a moment of inertia of 4 kg·m² about the axis. They turn at 45 rpm, then pull the dumbbells in to 0.2 m from the axis. Treat the dumbbells as point masses. Find the new speed n2 in rpm.
A hollow sphere starts from rest and rolls without slipping down a slope inclined at 15° to the horizontal. Use g = 9.81 m/s². Find its speed v after it has rolled 10 m along the slope.
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