Stability of a train
Ok, this one does not carry any points. It is only to feed your intellect; maybe even that little kid that lurks inside you and thinks about a train once in a while. With fascination and passion.
What keeps a train on the track?!
What keeps a train on the track?!
posted by littlecow at 5/19/2006 08:50:00 PM
5 Comments:
Don't understand any "ulterior" complications.....gravity keeps the train on the tracks(on a straight track anyway)
On curves,it would probably be a combination of normal reaction and friction(which provide the required centripetal force)that keep the train from flying off the tracks.
BTW,does ANYONE know anything abt lenscrafter's whereabouts ?!
If its that simplistic, would I post it here?!
Run through it, draw a picture and a force diagram. Hint: Why do rails have flanges? Another hint: Its really the rolling friction that keeps the energy loss at a minimum when compared to tyres in a car. Now, what happens when the flange rubs against the rails? It creates sliding friction - which results in substantially higher losses...
Further, you observe, when you travel in a train that it oscillates this way and that - laterally. Why is it that it does not slide off the tracks? You would counter by saying the flange keeps it in place. But those freaking nuts and bolts that keep the "sleeper" in place (a sleeper is what the wooden planks are called if i remember my grandpa right) - do you really think they can keep a compartment in place without failing? (each compartment weighs around 30000 kg)
Its more complicated than you think it is. But its also very beautiful. Thats the reason this question features on xyfactor! It took about 8 decades before people figured out the answer to this question - atleast partly. It was thoroughly solved about 120 years after the first victorian railroads took to the tracks. So, its really non-trivial dear matey!
On turns, it is a mere matter of radii of the inner and outer wheels as measured at the contact point. The differential in a car would take care of the velocity difference that the car needs to not skid. Since you wouldnt want to put a differential on a thirty ton compartment, you just design the wheels to have larger radii on the inside than on the outside. Beautiful design it is. When you cant change the angular velocity, you change the bloody radius. Basically if you had a little bit of brains, you would see the v = w times r. And you need higher velocity on the outer wheel; ergo you need to increase one of w or r. Bloody straightforward if one is not too daft.
aye aye saale! right on. the same explanation suggests a self-stabilizing action in a straight line.
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