An ultracentrifuge is spinning at a speed of 80,000 rpm. The rotor that spins with the sample can be roughly approximated as a uniform cylinder of 10 cm radius and 8 kg mass, spinning about its symmetry axis . In order to stop the rotor in under 30 s from when the motor is turned off, find the minimum braking torque that must be applied. If no braking torque is applied, the rotor will stop in 30 min. Find the frictional torque that is present under normal spinning conditions.

Apu , 6 Years ago

Grade 11