A flywheel of mass 120 kg with a radius of gyration of 0.25 m is accelerated uniformly from 200 rpm to 500 rpm. The driving torque is a constant 39 N·m and friction can be ignored. How long t does this take?
A uniform slender rod of mass 2 kg and length 2.3 m rotates about an axis O perpendicular to the rod, 0.6 m from its centre G. Find its mass moment of inertia IO about that axis.
A uniform slender rod of mass 10 kg and length 2.3 m is pinned at one end and held horizontal. It is released from rest. Use g = 9.81 m/s². Find the vertical force R that the pin exerts on the rod just after release.
A flywheel with a moment of inertia of 4 kg·m² spins at 2000 rpm. A brake applies a constant friction torque of 145 N·m. How long t does it take to stop?
A person stands on a frictionless turntable and holds a 5.5 kg dumbbell in each hand, 0.7 m from the axis. The person and turntable alone have a moment of inertia of 4.5 kg·m² about the axis. They turn at 20 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 uniform slender rod of mass 3 kg and length 1.9 m hangs at rest from a frictionless pivot at its top end. A 25 g bullet moving horizontally at 380 m/s hits the rod 1.31 m below the pivot and stays embedded. Find the angular velocity ω of the rod just after the impact.
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