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If a net nonzero torque is applied to an object that is able to rotate, the object will spin at an increasing angular speed. The torque causes angular acceleration.

In the case of a car engine, the engine eventually spins at a max constant rotational speed omega. Why does the angular speed not continue to increase due to the applied torque? Is it simply because as the speed increases also the resistive torques increase to result in a zero net torque? What is the nature of these resistive torques? Are they frictional torques?

Power= Torque* Angular speed. That said, if the shaft of an engine is connected to another gear that is half the diameter, this second driven gear will start spinning too, i.e. will experience a torque. But the driven will spin at twice the angular speed of the engine and not increase. Why does the speed of the driven gear not increase but remains stable at that fixed value? After all, there is a nonzero torque applied to it...

The second driven gear has a torque that is half the torque that the driving wheel applies to on it. Is this halved, smaller torque a torque that the driven gear can apply to a third gear or is it a torque applied to the driven gear itself?

Iguess a car engine can produce different amounts of mechanical power as it operates at different regimes. Power is energy produced per unit time. For instance, if we floored the accelerator pedal, the RPM would increase and more output power would be produced (the torque would probably decrease as the RPM decrease). There is surely a limit, a maximum power P_max that the engine can produce: that happens for for a certain value of torque and angular speed.

Can that maximum amount of power be produced at any gear when the engine spins at the RPM value? For instance, imagine that the max power speed was 50 RPM. If theengine spun at 50 RPM in first gear or 50 RPM in 2nd gear, would the torque automatically adjust to the right torque to give the max power output? Or does that max power out situation only occur at a specific gear?

thanks,

fog37

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# Torque and Rotational Power

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