Angular Momentum

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Alkatran
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We had a demonstration in physics, which I'm sure most of you have seen, of a wheel spinning very quickly maintaing it's orientation. (There is a string hooked to one end of the axle, and you expect the wheel to 'flop' downwards)

Now, I was just wondering what the math behind this is?

The spinning wheel has a high angular momentum in direction X while there is a torque from gravity in direction Y: after that...? This is definitely similar to it being difficult to slow an airplane rather than a ball.
 

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NateTG
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Alkatran said:
We had a demonstration in physics, which I'm sure most of you have seen, of a wheel spinning very quickly maintaing it's orientation. (There is a string hooked to one end of the axle, and you expect the wheel to 'flop' downwards)

Now, I was just wondering what the math behind this is?

The spinning wheel has a high angular momentum in direction X while there is a torque from gravity in direction Y: after that...?

The spinning wheel is typically called a gyroscope, and the movement is referred to as precession.

I'm pretty sure that it's possible to work things out starting from linear momentum to see that there's a net torque on the wheel as a rigid object by, for example, looking at the necessary change in velocity of point masses along various places on the gyroscope to tilt the axle while the wheel remains spinning.
 
  • #3
F=force
m=mass
0=theta
I wanna say F=mdcos0 but I am not 100% sure, and in physics when we are not 100% sure we say were just guessing.
 

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