# Why a bike can balane when the wheelse

1. Mar 22, 2006

### nzahra_ghasemi

why a bike can balane when the wheelse don't rotate but it is unstable
and when the wheeles rotate it will be stable equilibrum
it means that the maximum of E-x diagram change to it's minimum

2. Mar 22, 2006

### ZapperZ

Staff Emeritus
Did you just asked a question and then immediately answered it yourself?

Zz.

3. Mar 23, 2006

### HallsofIvy

Staff Emeritus
A bicycle can "balance" when it is not moving in the same sense that you can balance a broom stick on your nose! IF you get it exactly right and then don't move you are fine- but even the slightest twitch will cause it to fall: unstable equilibrium.

As for a moving bicycle, the simplest way to think about it is this: If you tilt a rotating wheel, it will tend to turn in order to conserve angular momentum. Riding a bicycle, if you lean to the right, the front wheel will automatically turn to the right, "catching" you as you ride forward.

4. Mar 23, 2006

### nzahra_ghasemi

i know the stable equilibrium is the min and the unstable equilibrium is the max of the diagram but i don't know how this happens in a bike

5. Mar 23, 2006

### nzahra_ghasemi

can you explain about "Euclid alone has looked on beauty bare" please

6. Mar 25, 2006

### HallsofIvy

Staff Emeritus
I thought I'd already responded to this but it didn't "take" apparently!

If you are referring to the poem, it is a sonnet by Edna St. Vincent Millay:

Euclid alone has looked on Beauty bare.
Let all who prate of Beauty hold their peace,
And lay them prone upon the earth and cease
To ponder on themselves, the while they stare
At nothing, intricately drawn nowhere
In shapes of shifting lineage; let geese
Gabble and hiss, but heroes seek release
From dusty bondage into luminous air.
O blinding hour, O holy, terrible day,
When first the shaft into his vision shone
Of light anatomized! Euclid alone
Has looked on Beauty bare. Fortunate they
Who, though once only and then but far away,
Have heard her massive sandal set on stone.