Nothing to do with programming : question for physicits

Jorgen Sigvardsson

Jerome Conus wrote: How can I calculate at which speed, the train will be too fast and will leave the rail ???? You'll have to calculate the artificial gravity of the train due to its speed through the corner. You'll find that formula in your physics book. Then combine that with the gravity pull by earth to get the total force vector affecting the train. Simple picture of train and forces:

+---------+

Fh | |
<---+----x |
| | |
dy | | |
+----+----+
dx |
v Fv

The above picture is a simplification of the train. You've got two major forces: Fh and Fv. Fh, Force horizontal, is the artificial gravity due to the speed/corner. Fv is the earths gravity pull. The train will fall when Fh * dy > Fv * dx, where dy and dx are horizontal and vertical distances respectively, from the outmost train wheel to the mass center of the train. So basically, when the momentum is stronger counter clockwise than clockwise, the train will fall over. -- I'm coming out of the closet: I :love: VB

Roger Allen

Paul Watson wrote: location of Biggs at the time and how much money is on the train. :-D Roger Allen Sonork 100.10016 Were you different as a kid? Did you ever say "Ooohhh, shiny red" even once? - Paul Watson 11-February-2003

Giles

For one thing your going to need to know the centre of gravity of the train. Also are you assuming that if one carrige goes the others go, which in real life would not be the case? This can be easily investigated by looking at a cross section of a train. First look at this from the point of view of a train at rest, where someone is trying to push it over by hand - not likey either. You need to know the vertical acceleration (gravity - not hard) and the lateral force ( this will later come from going around the corner at speed), along with the centre of gravity. You can work out the horizontal force required to tip the train over at rest, by combining the two force vectors until they are outside the wheel base - at which point the train will start to tip. The acceleration from going around a bend is (me thinks - been a while) acceleration = angular velocity * radius Once the acceleration from going around the bend surpases the at rest push over acceleration then your there. And if that make sense then god help you. :laugh: Quote from a clever bloke : "I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones." - Albert Einstein

Kastellanos Nikos

What is the height of each vagon (actually where is the mass center) and what is the distance between the 2 rails? I think a vagon leaves the rail when it slope to the point that it's mass center goes outside the rails. :) One idea is to devide the vector of the speed into 2 perpendicular vectors, one pointing to the direction of the rails. The other vector whould be the power that 'push' the vagon outside the rail. - - - - - - - - - - - - - - - - - - Memory leaks is the price we pay \0 01234567890123456789012345678901234

Paul Watson

Roger Allen wrote: and how much money is on the train Eeeeeeeeexactly. :-D

Paul Watson
Bluegrass
Cape Town, South Africa

Macbeth muttered: I am in blood / Stepped in so far, that should I wade no more, / Returning were as tedious as go o'er Want a job?

Christopher Duncan

Paul Watson wrote: Surely you need more info though. Rail depth, depth of groove in train wheels, is Fat Bastard on the train, location of Biggs at the time etc. etc. Along with the average width of a horse's posterior as a constant, for validating the proper width of rail placement... Chistopher Duncan Author - The Career Programmer: Guerilla Tactics for an Imperfect World (Apress)

Christopher Duncan

Kastellanos Nikos wrote: What is the height of each vagon And how bad is the poetry? Oh. Sorry. Thought that was Vogon... Chistopher Duncan Author - The Career Programmer: Guerilla Tactics for an Imperfect World (Apress)

Jerome Conus

Weiye Chen wrote: looks like a homework assignment Come on guys....I finished my studies 7 years ago, this has nothing to do with homework.... But I agree that if, by that time, I would have be keener at doing my homeworks, I wouldn't be posting this question today !!! ;-) Jerome

benjymous

What? A physics question in the lounge?!? You'd be better off in the Visual Physics++ forum, or perhaps the Physics.NET forum ;P -- Help me! I'm turning into a grapefruit!

Paul Watson

benjymous wrote: Physics.NET forum A train derailment hypothesis is not safe code so would need the appropriate markings in .NET. VP++ is probably the better language.

Paul Watson
Bluegrass
Cape Town, South Africa

Macbeth muttered: I am in blood / Stepped in so far, that should I wade no more, / Returning were as tedious as go o'er Want a job?

Jerome Conus

Paul Watson wrote: Wait... my divine knowledge of celestial parephenalia tell me that... wait... wait... wait... this is a homework question! If it is not then my apologies, but it reeks of it and is no better than a programming homework question. I admit that my question smelled like homework, but after a quick look at my profile you would have notice that studies are now several years behind me :-) But thank you for pointing out that my question was lacking important informations about Fat Bastard and Biggs ! ;-) Jerome

benjymous

And of course Visual High School Physics is worth avoiding like the plague, as it teaches you rubbish like the atom being the smallest datatype. It's perfectly good as a learning language though -- Help me! I'm turning into a grapefruit!

Paul Watson

Jerome Conus wrote: I admit that my question smelled like homework, but after a quick look at my profile you would have notice that studies are now several years behind me But thank you for pointing out that my question was lacking important informations about Fat Bastard and Biggs Jeeesh, giving me something to work with here. Now I have to post a stupid reply admiting I can't figure out how to argue with you any further. Throw me a frikin bone man! :rolleyes: Oh, and we should never stop learning. Plenty of guys here in their 50s who are doing part time course at Uni.

Paul Watson
Bluegrass
Cape Town, South Africa

Macbeth muttered: I am in blood / Stepped in so far, that should I wade no more, / Returning were as tedious as go o'er Want a job?

Jorgen Sigvardsson

benjymous wrote: as it teaches you rubbish like the atom being the smallest datatype. Well, it doesn't get any better at University level either. Then you're taught that strings are the smallest datatypes! :omg: Sheesh. I wonder if I get a Nobel prize if I do some research on char? :cool: -- I'm coming out of the closet: I :love: VB

Jerome Conus

Christopher Duncan wrote: Along with the average width of a horse's posterior as a constant, for validating the proper width of rail placement... No kidding : the width of a horse is VERY important !!! :-) Did you know that the width of a horse's posterior is the origin of the size of the booster rockets of the Space Shuttle ??? In english : http://info.mountains.net.au/rail/horse-ass.htm[^] For french speakers : http://lwdr.free.fr/disjonctes.html#L'ESPACEMENT%20D'UN%20CUL%20DE%20CHEVAL[^] Jerome

Kastellanos Nikos

Christopher Duncan wrote: And how bad is the poetry? Oh. Sorry. Thought that was Vogon... uh, those greek QCERTY-type keyboards. They make you do all sort of strange mistakes... ;P - - - - - - - - - - - - - - - - - - Memory leaks is the price we pay \0 01234567890123456789012345678901234

Andreas Saurwein

Kastellanos Nikos wrote: uh, those greek QCERTY-type keyboards. So you are programming in W++, right? :)

powerful binary resource reuse - another word for "no sources, you are stuck with a pain-in-the-a## COM component"

Lost User

With a bit of work you can probably get it down to 50 variables: Centre of gravity of train Camber of rails Amount of oil/grease/dirt on rails etc..... Elaine :rolleyes: The tigress is here :-D

Roger Wright

The mass in this case is unimportant; the radius of the turn and the location of the center of mass are critical. The outer rail in the turn forms a constrained pivot point, while the inner is unconstrained. The line between the outer rail and the center of mass lies at an angle, Ø, with respect to the horizontal, so the gravitational acceleration can be resolved into a tangential component (directed inward) and a radial component (directed along the line toward the rail), both acting as though applied at the center of mass. The centripetal acceleration is horizontal, acting also through the center of mass, and can be resolved into a tangential component (directed outward) and a radial component (directed upward). This centripetal acceleration is given by ac = S2/R. The speed, Sc, at which the tangential acceleration due to gravity equals the tangential acceleration due to turning is critical. Any higher speed will cause the center of mass to be accelerated toward the outside of the turn, eventually causing the train to tip, as the net tangential acceleration will be toward the outside of the turn. Once the center of mass crosses the line of the outside rail, gravitational force alone will be sufficient to drop the train to the siding. Determining the point at which this occurs requires the mass, M, to be known, as the net tangential acceleration (resolved back into a horizontal component) will create a force directed sideways to move the center of mass the width of a horse's ass and beyond the balance point directly over the outer rail. The time required to accomplish this can be calculated, and yields the point on the curve's circumference where the train is inevitably doomed. The solution details are trivial, and are, as usual, left as an exercise for the student. :) It is ok for women not to like sports, so long as they nod in the right places and bring beers at the right times.
Paul Watson, on Sports - 2/10/2003

Eddie Velasquez

Jerome Conus wrote: How can I calculate this position where the train will leave the rail ? It depends on how drunk the driver is. :)

There are only 10 kind of people in the world: those who understand binary and those who don't.