# Why doesnt net torque cause angular velocity to increase upto infinity?

by ashutoshd
Tags: angular, increase, infinity, torque, upto, velocity
 P: 5 If i have a shaft & i'm applying a driving torque D at one end & at other end there is resisting torque R due to bearing friction, etc. Then if D>R, i have net torque = moment of inertia times angular acceleration. Since the ang. accln is constant with respect to time, will the ang. speed of shaft keep increasing till infinity? If the answer is yes, then why doesnt this happen to motors & engines @ low or no load? Another doubt is that by conservation of energy we have input power= output power + losses, so if i am giving finite input power, the output power has to be finite. Since rotational kinetic energy of shaft is half * MI * square of angular velocity, angular velocity cannot be infinite as that would make output power infinite, right? Please help this is so confusing
 P: 217 Generally, the resisting torque R increases as angular velocity does, until D=R and the stationary state is reached
 P: 403 In motors, as the angular velocity approaches the synchronized velocity, which depends on the frequency of the electric power and also on the number of poles in the winding, the torque decrease. in absolute no-lode, the torque becomes zero. This happens because when the rotor is rotating with the same speed as the magnetic field is rotating, no current is induced in the rotor. For engines also there is a system to reduce the fuel to keep the speed low, unless you press the gas pedal.
Engineering