Roller Coaster Physics question

I'm in my second year of high school physics and even though I'm pretty much done studying mechanics an interesting discussion came up. I'm familiar with the idea that a coaster will run faster when the temperature is hot out. I was wondering what the physical reason for this was. I'm interested to hear the answer. We also talked about being able to remove the piece of track at the top of a loop and still have the car make the loop if it traveled at the critical speed. That would be a cool ride! Your help would be greatly appreciated.

I just thought that it is the grease heats up and allows it to run faster. I'm not very sure though.
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It's his turn to feast, when you ride the Son of Beast.

Roller coasters run on bearings. Bearings are oiled. Oil haas a lower viscosity at higher temperatures. Simple as that.

Critical speed for a loop... this is one of those things that physics people dream up that engineers dash. There's too much uncertainty in the environment to EVER have ANYONE even attempt this, until we live in a world of gravatic and environmental effectors.

It would work, if the train was a point, like it would be treated in a physics problem. The problem is if one person puts their hands up, the CG shift is enough to throw the train off and kill everyone onboard. Never happen. A car without upstops is close, though, in that it only has "half" of a normal track and can still navigate a loop. I don't want to ride it though, again the uncertainty.

Physics is great but I'd never trust a physicist to design anything my life depends on

Heat reduces friction in the wheels, allowing the train to gather more speed and keep that speed longer.

Comatose said:
"Physics is great but I'd never trust a physicist to design anything my life depends on"

So I guess we'll never see you on an airplane or boat huh?

Anyway, it is *quite* possible for a vehicle to complete a loop with out the top portion of the track there. It has been done many times with models and such. However, there are many reasons why that wouldnt be practical for an amusement park ride. As noted, little things like a gust of wind can screw up things horrendously, and that's just not a risk most are willing to tolerate.

But, a rider thowing up their hands would NOT cause a shift in center of gravity. It *would* however have an effect on the drag of the train which in turn could throw things off. Additionally, if the vehicle is a conventional coaster train (ie multiple cars) the relative motion of the cars to themselves would pose quite a formidable problem (not impossible, just difficult, need vibration theory). Then there's that whole thing of getting the car *back* onto the track...
lata,
jeremy
--who has actually been thinking about this problem since 1992...one day I *WILL* figure it out...

A rider putting his hands up would shift the center of gravity. Not dramatically considering the train weighs 20,000 lbs and your hands weight 10, but it would shift it.
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The legend lives!

Fine, if you want to take it to that level then a person laughing, screaming, or hell just breathing will shift the CG as any slight mass displacement is indeed a displacement. But for all practical intents and purposes, there is not going to be any appreciable shift.
lata,
jeremy
*grumble*cant see the forest because of the trees*grumble

...this could be solved by say...combining a floorless and inverted train into one. Then you could have the floorless track end just as it changed to inverted track, but you'd never put a break in the track.

In theory, this would be ideal if it was to change on the brake run since it could be controlled better.

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In warmer weather, the track of the coaster will expand. Now I'am not sure with all of the wheels and track stuff, but in warmer weather the wheels on the trains would have a tighter fit on the track. Like I said before, I am not sure if this would speed up or slow down the car.
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Take a good look at Six Flags Worlds of Adventure because in a few years the Sea World side will look exactly like it does, a zoo.

Great Idea CPgenius. Truly.

Yeah willthethrill, it would really freak out the GP sitting it front to see the track they are running on suddenly end.

Bubba, I thought about that too, and I'd think that it would cause more fricton because the track expanding. Maybe not though...

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Mayday - Memorial Day Weekend - Nonpoint, Nickelback, Oleander, Staind
Ozzfest - June 8 - Drowning Pool, Papa Roach, Linkin Park, Disturbed, Black Sabbath
Awake Tour- June 15 - Darwin's Waiting Room, Puddle of Mudd, Deftones, Godsmack

The train expands too though, not just the track.
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Does CCI know how to make a bad coaster?

By that, do you mean that the wheels expands too? If so, there would be even more friction...

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Mayday - Memorial Day Weekend - Nonpoint, Nickelback, Oleander, Staind
Ozzfest - June 8 - Drowning Pool, Papa Roach, Linkin Park, Disturbed, Black Sabbath
Awake Tour- June 15 - Darwin's Waiting Room, Puddle of Mudd, Deftones, Godsmack

Not just the wheels everything, everythign expands in the heat and shrinks in the cold. I think the difference in gauge would be little to none as far as hot or cold. I dont know if the wheel would expand much as they are running on teh track and fricvtion heats them up a lot anyway, besides nylon doesn't expand as much as steel, at least I don't think. The real difference is the bearings as was stated before, the warmer they are the easier and faster they can turn.
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Does CCI know how to make a bad coaster?