Downhill weight

[SlimJim1284]

I think this is a good question. I know we have heavy *** cars- and i get pissed when i lose to my friends suped up civic si. i have more horsepower but his car is so frikin light. anyway, when i was a little kid i was a cubscout (shut up i know it was ghey but i was just 8) and when we had the pinwood derby the heavyest car was the fastest when it went down the hill. So i was thinking if i raced the lightweight civic down a hill won't i beat the shyt out of it? Won't a heavier car with more power do better going down a hill?

[Wicked 3800 V6]

PE at the top of the hill === KE at the bottom. Equate mgh=(1/2)mv^2
The m's cancel out. It's not a matter of which car is heavier, in fact such a heavy car would face more friction, as friction is a function of the normal force.
At least, that's what I'd think.
-Rob

[Justin Kirkham]

the heavier will be slightly faster, though I cannot see it making any difference on our scale.

-Justin

[AZ3.8Camaro]

Thats like asking "If I dropped my car and his car, which would hit the ground first?"

[EDIT] Actually he might beat you there too as his car is smaller and probably has less drag. :D

[ February 25, 2003: Message edited by: AZ3.8Camaro ]</p>

[95Batmobile]

Ours cars are very aerodynamic though, sometimes I can cruise downhill and let off the gas, without putting it in neutral or anything, and my car will not slow down.
I used to follow my girlfriend home for the weekends and i'd always pass her going down hill even when I had let off the gas. Her Jetta just didn't coast very well [img]tongue.gif[/img]

[Camarorulz]

The only thing that affects downhill speed is drag coefficient. Weight doesn't matter at all. You can drop a 5 lb weight and a 10 lb weight from the same height, and they will hit the floor at the same time, every time.

[silvachris1]

I'm not sure how this applies to the topic, but the downhill passing on your girls jetta could have something to do with the gearing, I have no clue as to what gearing the jetta has, but yours could be lower (dunno, I'm guessing .308's? in yours). Something else, your timing might be off slightly, causing it to pull even more than one idling normally. Who knows, just a thought.

[Takumi Fujiwara]

LoL, Im glad to say, at the races I never lost to a civic that I didnt beat on a 2nd match and 3rd for bragging rights. some pretty tricked. The Idea is if u know u can get a rematch never show ur potential the 1st time. Stupid ricer and his turbo has never heard of heat =)

[navyblue2000]

i remember my last pinewood derby...

scoutmaster's son's car lost a wheel...so they re-ran the heat. he advanced.

Next round, I lost a wheel. did i get to run again? NO. I got knocked out :( :rolleyes: :mad:

[Dominic]

Also a heavier car tends to has more forward momentum for a given speed, so the wind drag doesn't tend to slow it down as much (even though the rolling resistance is more, but lets not get into that). This is why a 20,000lb truck tends to not slow down a heck of a lot even though it has the drag coefficient of a dixie plate turned the wrong way into the wind!

And no, mass does not matter, until you start comparing forces acting on objects like wind against a bullet vs a piece of popcorn with the same drag coeff and frontal area etc etc etc. That popcorn is far lighter so the wind drag affects it more.

[Redsix]

First of all, who the hell races downhill?? :eek: I'm sorry but it sounds pretty stupid to me and the fact that you have to race downhill to beat a honda is the ultimate ricer thing I've ever heard. :rolleyes:

P.S. All of this physics talk is pretty lame too. Try to sit there and calculate the drag force effect on a golf ball and then got hit one for real, theory and reality will make you think about the credibility of some of the previous statements. Reality is a little bit more involved then just summing vectors or whatever crap they feed you in school. Just a thought, and a little venting. :D

[ March 14, 2003: Message edited by: Redsix ]</p>