A flywheel of mass 110 kg with a radius of gyration of 0.4 m is accelerated uniformly from 100 rpm to 1100 rpm. The driving torque is a constant 77 N·m and friction can be ignored. How long t does this take?
Rigid-body rotation worksheet with answers
A flywheel of mass 250 kg has a radius of gyration of 0.5 m about its axis. It spins at 900 rpm. Find its kinetic energy Ek in kJ.
A uniform slender rod of mass 3 kg and length 1.7 m is pinned at one end and released from rest in a horizontal position. A small ball of mass 3.5 kg is fixed to its free end. Ignore friction and use g = 9.81 m/s². Find the speed v of the free end as the rod swings through the vertical position.
A 4 kg block hangs from a light cord wrapped around a pulley, a uniform solid disc of mass 6.5 kg and radius 0.45 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 solid cylinder starts from rest and rolls without slipping down a slope inclined at 10° to the horizontal. Use g = 9.81 m/s². Its radius is 0.05 m. Find its angular velocity ω after it has rolled 5.5 m along the slope.
A uniform slender rod of mass 2.5 kg and length 0.8 m hangs at rest from a frictionless pivot at its top end. A 30 g bullet moving horizontally at 240 m/s hits the rod 0.52 m below the pivot and stays embedded. Use g = 9.81 m/s². Find the largest angle φ from the vertical through which the rod swings.
Answer key
- 1. t = 23.94 s
- 2. Ek = 277.6 kJ
- 3. v = 6.088 m/s
- 4. α = 12.03 rad/s²
- 5. ω = 70.69 rad/s
- 6. φ = 107.4 °
Full step-by-step solutions: practise this topic on examproblems.com.