What is Rotor?

“A hollow cylindrical shell when rotated about its own axis is called rotor.”

Explanation & Mathematical derivation:

Consider a person enters, rotor and closes its door. Ile stands up against the wall of the rotor. The rotor is put into rotation by pressing a button of motor. The floor below his feet is opened when it reaches a particular speed. It is observed that man does not fall downward but remains pressed against the wall of the rotor. The minimum speed of rotation which prevent the man from falling can be calculated as:

Consider man of m stands up against wall of rotor having radius R. The static friction f(s) = μN acts against gravity force mg. The minimum speed of rotation which prevent the man from falling downward is ω.

Following forces are acting on the man:

• Weight of man acting vertically downward.
• The static frictional force acting vertically upward.
• Normal force of the wall on man.

Frictional force must balance the weight force if man have to remain clung to wall.

Frictional force must balance the weight force if man have to remain clung to wall.