A pendulum is made of a uniform slender rod (3.5 kg, 1.5 m long) pivoted at its top end O, with a solid sphere of mass 7 kg and radius 0.2 m fixed to its lower end. The centre of the sphere is 1.7 m below O. Find the mass moment of inertia IO of the pendulum about O.
A pendulum is made of a uniform slender rod (5 kg, 1 m long) pivoted at its top end O, with a thin solid disc of mass 3 kg and radius 0.1 m fixed to its lower end. The disc swings in its own plane and its centre is 1.1 m below O. Find the mass moment of inertia IO of the pendulum about O.
A flywheel with a moment of inertia of 14 kg·m² spins at 400 rpm. A brake applies a constant friction torque of 35 N·m. How long t does it take to stop?
A flywheel with a moment of inertia of 14 kg·m² spins at 2000 rpm. A brake applies a constant friction torque of 30 N·m. How long t does it take to stop?
A person stands on a frictionless turntable and holds a 4.5 kg dumbbell in each hand, 0.9 m from the axis. The person and turntable alone have a moment of inertia of 2 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 thin hoop of mass 2.5 kg rolls without slipping at 4 m/s. Find its rotational kinetic energy Erot.
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