Re: [Phys-l] Bicycle question

[sampere <sampere@physics.syr.edu>]

That's not the original question. We're only trying to balance, not make 
a turn.

If I want to turn left, I initiate that turn by quickly steering to the 
right and back. This causes my bike to lean to the left where I easily 
make a left turn. I think this is rather easy to explain without using 
angular momentum of the wheels. Angular momentum of the massive rider is 
a different story...

Consider a mass at the end of a stick. Balance the free end of the stick 
so the mass is high in the air. (A variation, what's easier to balance, 
mass far from your hand or closer to your hand?) Ok, so we're stuck with 
this mass up in the on the end of a stick and you're trying to balance 
it. You accomplish this by moving your hand back underneath the mass as 
it rotates.

Now, suppose I limit the speed that you're allowed to move your hand. 
Does this make it easier or harder to balance? When you're rolling very 
slowly, does this limit the speed you can bring the wheels back 
underneath? Does rolling very slowly make it more difficult to balance? 
As with anything, practice make perfect. I can balance at a stoplight. 
What's the angular momentum of my wheels???

Again, it's not angular momentum, it's your response to get the wheels 
underneath your butt.

Sam

Chuck Britton wrote:

> At 6:52  -0400 on 8/23/06, Martha Takats wrote concerning Re: 
> [Phys-l] Bicycle question :
>  
>
> > Isn't this essentially the same reason it's harder (takes more force)
> > to turn a corner when you're going fast (greater linear momentum)?
> > In this case it's angular momentum (sorry Sam). Tipping changes the
> > angular momentum of the wheel and so requires more torque when the
> > wheel is turning fast.
> > Martha Takats
> >    
>
> Indeed the angular momentum becomes WAY more important on a motorbike 
> with greater speed and moment of inertia.
>
> When riding a straight path at speed - making a quick turn to the 
> LEFT requires the rider to PUSH FORWARD on the LEFT handlebar. This 
> is hard to explain without resorting to Sam's nasty Angular Momentum.
>
> (The steering effect of the the tires profile can be well illustrated 
> with two foam cups taped together rim to rim. The double cone steers 
> as it is tipped. none angular mom. effect)
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