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Mulholland>SCC
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lol, thanks for posting!
 

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"He is so light weight he can't even speak"... LOL
 

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Very interesting!
They did well considering their budget.

Maybe I'm missing something, but I think they made a mistake by adding ballast (they brought it up to the max allowable weight). Since all the carts are powered by the same force (32 ft/sec/sec) regardless of mass, it seems to me that all the ballast does is increase the frictional losses. Anyone?
 

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I would have thought the ballast would add weight to help them get down the hill faster, although adding more friction, would help them stick to the corners better at speed.
 

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I like how the second run against the white guy, the gadget dude tried to block off the Lotus from passin him going down the hill XD
 

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I would have thought the ballast would add weight to help them get down the hill faster...
I think that's what they thought, but I just repeated Newton's famous experiment (I used an apple and a grape) and it seems gravity is still working the same nowadays. So the weight can not help acceleration. I suppose a lower CG would help a bit in the turns, but it seems to me that any such gain would be outweighed by the losses in friction (rolling resistance, bearing friction, steering vibration). Just a SWAG, though. I'd also guess that the difference the ballast makes (positive or negative) is probably much smaller than the effect of the driver's performance.
 

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the ballast actual helps with momentum. yes, straight down you accelerate the same pace, but frictional forces will be "relatively similar" at all weights so the force acting on it has to perform more work to slow down the heavier car (sum of work, conservation of momentum). the heavier car will carry its speed further.

that's how we learned it in phsycis (i think :shrug:)
 

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re: ballast

Galileo didn't compare a feather to a lump of lead, or he might have got a different answer, except in a vacuum, which he also didn't have available.

Max weight means max gravity force - minus the drag, which is more dependent on area, and not changed by the ballast, unless you make a sail out of it! It's the nett difference in those forces that gets divided by the mass. -poke-
 

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i think we should host a "gravity race" of our own in SoCal and dispense of all these rumors on the road :)

i am sketching out my desing now :evil:
 

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Neat video.
As for the ballast question--that's why max weight rather than min weight is specified. Or just ask any bicyclist who will go faster coasting down hill--the 110 lb lady on a 22 lb bike or the 180 male on a 27 lb bike :D (all else being essentially equal, of course).
 

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Galileo didn't compare a feather to a lump of lead, or he might have got a different answer, except in a vacuum, which he also didn't have available.

Max weight means max gravity force - minus the drag, which is more dependent on area, and not changed by the ballast, unless you make a sail out of it! It's the nett difference in those forces that gets divided by the mass. -poke-
It suddenly occurs to me I meant 'Newton.' Oops.

I follow your second point: F = MA, then take out the drag, then divide by the mass! But... the drag is changed by the ballast - the drag is both aerodynamic and mechanical. The mechanical drag is at least somewhat affected by the weight of the car. I guess it's a matter of which is the bigger factor (and at what speeds: aero drag increases proportional to the square of the speed; what happens to friction?). I'm not arguing with you directly, just trying to think it through. I don't know much about this stuff, that's why I'm using question marks.

the ballast actual helps with momentum.....the heavier car will carry its speed further.
I'll buy that. But wouldn't a momentum strategy only pay off if there were flatter sections on the track where the cars were decelerating? Whereas it appears in the video that the cars continued to gain speed for the large majority of the run.

Neat video.
As for the ballast question--that's why max weight rather than min weight is specified. Or just ask any bicyclist who will go faster coasting down hill--the 110 lb lady on a 22 lb bike or the 180 male on a 27 lb bike :D (all else being essentially equal, of course).
I don't have a bicyclist handy. Which is it? :)
 
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