angular momentum

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Just a random question...

If you're riding a bike on thin ice with , and the wheels are rotating just as fast as they normally would when you're riding, will you fall down? (let's assume you're not a newbie on a bike)

[appianway]

It shouldn't really make all that much of a difference (unless factors other than angular momentum play an exceptionally large role in balance on a bike). The wheels still have a tendency to rotate on their own axes; the only difference is that there isn't linear momentum.

I could be wrong though. I've done minimal angular momentum!

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Yeah I'm actually not quite sure myself how angular momentum keeps a normal bike upright (I was lazy in semester 1)
All I know is angular momentum must be conserved...

So you're saying the bike would stay upright? Yeah that's what I reckon as well, I don't know how to explain it though


Oh nevermind, actually, just thinking about angular momentum, it is a vector perpendicular to the face of the wheel, so if you fall down, the vector changes direction and angular momentum is not conserved XD
I used to think only the direction of spin mattered

[QuantumJG]

Just a random question...

If you're riding a bike on thin ice with , and the wheels are rotating just as fast as they normally would when you're riding, will you fall down? (let's assume you're not a newbie on a bike)

well since you have no friction your Tyres won't be able to move! my guess is that you would fall over due to there being no friction.

[appianway]

Unless the bike already has linear momentum, in which it'd continue to move irrespective of the motion of the wheels.

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Even though there is no friction between the tyres and the ground, the tyres would still be move when you pedal them.

Also, I don't think you even need linear momentum. You can be completely stationary, but as long as the tyres have angular momentum you won't fall down.

I guess the lack of friction would make it easier to fall down, but I'm not sure about that, since you would still need to conserve angular momentum somehow.

[appianway]

Yeah I know there'd be conservation of angular momentum for the balance, but what I was saying was that you don't need the wheels to turn to move (if there's linear momentum it'll continue in its path).

[kamil9876]

I would rule out linear momentum having anything to do with this, simply because you can change to a reference frame where it would be stationary; but both reference frames must agree on whether it falls down or not. To check whether a certain phenomena depends on some variable, it is good to see if it also works in other reference frames.

I remember some demos long way back where the lecturer chucked a rotating wheel in a suitcase, and suddenly it became uber hard to move it sideways, so angular momentum does ring a bell(also, all inertial reference frames agree on angular momentum so it seems like a better candidate)... but meh i won't have to do any more physics after sem1 next year  8-)

[TrueTears]

but meh i won't have to do any more physics after sem1 next year  8-)

hahah I assume all maths?

maths >>>>>> all science

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maths >>>>>> all science

lies
 

[TrueTears]

maths >>>>>> all science

lies
 

lol I was kidding but a bit of bias there I do admit haha

[/0]

maths >>>>>> all science

lies
 

lol I was kidding but a bit of bias there I do admit haha

lol i have bias too 

[QuantumJG]

I would rule out linear momentum having anything to do with this, simply because you can change to a reference frame where it would be stationary; but both reference frames must agree on whether it falls down or not. To check whether a certain phenomena depends on some variable, it is good to see if it also works in other reference frames.

I remember some demos long way back where the lecturer chucked a rotating wheel in a suitcase, and suddenly it became uber hard to move it sideways, so angular momentum does ring a bell(also, all inertial reference frames agree on angular momentum so it seems like a better candidate)... but meh i won't have to do any more physics after sem1 next year  8-)

That sounds like the right answer. I can't believe I forgot first year physics demo (I even had to do an assignment related to this - :S).

But yeah what happens is you give a tyre angular momentum and it requires a lot of work to change the angular momentum vectors' direction, thus the tyre doesn't tip over but process about it's axes, but the main reason is angular momentum.

[appianway]

This is slightly off the bicycle topic, but does anyone here know about precession? It's quite cool.

[QuantumJG]

In first year physics we were shown the bicycle wheel demo and the professor tried to qualitatively explain precession.