# Impulse in a flywheel-to-flywheel situation

1. Jan 27, 2006

### swedish_lunacy

Cognitive superiors,

I am trying to calculate the maximum torque that a flywheel of a given angular momentum can output when "instantaneously" ( I think this is my problem ) connected to another flywheel.

From what I can see it seems that as the time taken to couple the flywheel to the output shaft approachs zero, the torque output approaches infinity.

Does this mean that you can essentially create a huge, huge torque from "instantly" coupling a small flywheel to something ? Seems wrong to me.

Taking a real workd situation. If I was trying to grab a large moving flywheel it would try to rip my arm out of it's socket, if I were to grab a small moving flywheel such that the contact-time produces the same maximum torque then I may be able to stop it ? Or is this more to do with work than torque ?

Cheers
Nick

2. Mar 23, 2006

### NateTG

The instantaeous torque does indeed go to infinity. As with many other physical procesees, that typically means that some assumptions that you're making are probably invald (in this case rigidity).

In real life, there is a limit on how rigid materials are, and they will deform in high stress enviroments. With the right equipment, I'm sure you could twist a heavy I-beam without any restraints other than the I-beam's intertia.

Similarly, colisions can produce spectacularly large peak forces, but at some point the materials involved will fail in a variety of ways.

3. Mar 23, 2006

### swedish_lunacy

Gotcha, ie. no material is infinitely rigid therefore no torque is ever infinitely large.

Thanks
Nick