We all know this.... i just want to know the physics behind this everyday action
How can we easily balance ourselves (stay upright) on a moving bicycle (or bike) but the same thing is impossible when a try on a stationary two-wheeler?
2007-02-21 20:09:08 · 7 answers · asked by rEdshiFt 2 in Science & Mathematics ➔ Physics
LOL... I have to admit...I got a lot of chuckles out of some of the answers above...I think many of them were on the right track but not really understanding completely how a bike works and the complete set of physics that are at work.
I'm sorry .. I mean no offense to anyone. And I didnt read the other answers all carefully...however... I didnt notice anyone mentioning the actual reason.
Take a bike and run along side it...balancing it as you run... If you run fast enough...and let go as you run (on a smooth flat surface) you will note that the bike will continue to stay vertical and will roll along beside you. I take my daughters bike to school to pick her up while I am riding my own bike using the very principle involved. People look and say WOW..but its really practically no effort.
We wont get into how a bike or motorcycle is turned..we will just address your question.
The bike is balanced because youre riding a pair of gyroscopes...and angular momentum **is** involved. I will point you to a link that better describes how a spinning gyro (essentially what a bike wheel is) stays on its same plane...UNLESS...you apply angular force...to which it will resists..but with enough force it will change angle.
While you sit in on the bike, the two wheels want to (and have a very strong force - YOUR SPEED spinning them .. so the faster you roll, the easier it will be to stay balanced.) stay at the same angle they are spinning at. This is how come the bike, and a motorcycle if you were able to leap off of it..would keep going upright untill something caused a change (obstacle or such)...or untill the wheels didnt have enough rotation to counteract the weight that would pull to one side or the other.
The force (as a result of your speed laterally) that is generated by the spinning wheels is enough to keep the bike upright...and as long as you have a sense of balance, you minimize the forces to one side or the other that would counteract that gyroscopic benefit. When youre standing still...you do not have the benefit of the gyros to keep the bike at the original angle...and hence the balancing is all left up to you...
Found this nice simple article ...
http://socrates.berkeley.edu/~fajans/Teaching/MoreBikeFiles/BikeQuestions.htm
And this one too...
http://science.howstuffworks.com/gyroscope1.htm
2007-02-28 04:11:32 · answer #1 · answered by Rob P 2 · 0⤊ 0⤋
This has nothing to do with angular momentum - if you think so you do not grasp even basic physics (if it were, the same principle would stop you turning a corner on a moving bike).
It is because the front forks are bent. This causes the front wheel to steer itself out of tilts (try it with a stationary bike). This only works if you are moving.
2007-02-21 20:54:27 · answer #2 · answered by Anonymous · 0⤊ 2⤋
It's not impossible to balance on a standing cycle, just impossible for most of us. There was an outstanding magazine feature showing trials rider Pam Fish (I think that's who it was) stop her motorcycle, do a handstand on the front fender then ride away. I tried this and got as far as stopping the motorcycle. I guess my grasp at physics sucks.
2007-02-22 05:27:42 · answer #3 · answered by aGhost2u 5 · 0⤊ 1⤋
Let us take another simple example.
Can we stand a ruler on a finger ?
Certainly not when hand is at rest. But if I can move my hand horizontally I can stand the ruler. Practice yourself and you will find that if ruler's top at the right side of the vertical plane you have to move your hand towards right to keep the ruler erect.
Why is this ?
Because to balance the torque of center of mass w.r.t. your finger. When you shift ( quickly ) your hand you just cancel the torque.(mg*r where r = 0) .
That is if you can stand the motor cycle at perfectly vertical plane( for balanced motor cycle ) Then it will stand erect. But it is quite difficult to stand that way.
When motor cycle moves it moves on micro gig gag line to cancel torque. When your handle is at write side there is a torque at write side and vice versa.
So to keep the vehicle erect continuously you have to move the handle from left to right and right to left(that we normally can not anticipate ). If there is sudden jamming to handle you will fall down.
2007-02-21 21:48:34 · answer #4 · answered by Dilip Dey 2 · 1⤊ 0⤋
While the cycle is moving there is a force of friction between tyres and roads. Force of friction results into a gravitational force not due to gravitational force of earth but due to mass of the cycle which binds the tyres on the surface its moving , while at standstill there is no friction force and no resultant gravitational force due to mass of cycle, but there is gravitational force of earth which keeps fallen cycle on earth rather than cycle paying substitutes to the air planes.
2007-02-22 12:49:08 · answer #5 · answered by Sandeep 2 · 0⤊ 1⤋
This is an example of the law of conservation of angular momentum. It is the same principle that keeps a top up.
2007-02-21 20:14:14 · answer #6 · answered by Roy E 4 · 2⤊ 0⤋
there's a gyroscope that demonstrates the theory of centrifugal tension. while the wheels are turning, the strain is thrown vertically, protecting the bike upright. while the wheels are stopped, gravity takes over, foremost to skinned knees.
2016-12-17 16:01:30 · answer #7 · answered by Anonymous · 0⤊ 0⤋