I need advice on how to make a car


by swati621621
Tags: advice
swati621621
swati621621 is offline
#1
Oct9-04, 01:23 PM
P: 2
Hi there everyone,
For physics, I have to make a car entirely out of food. And, I'm really not sure how I should proceed. What I did think was that I'd make it out of graham crackers as the body, Fudge Shoppe cookies with the hole in them as the wheels, and Cow Tales as the axles.
Now, I'm not sure if making the axles longer/shorter makes the car go faster. Or, does making the wheels smaller/bigger impact how far it goes? The key is that my car needs to go far, not fast.

The ramp that it's going to go off of is 30 degrees, so I was thinking, the heavier it is, the further it will go.

Well, I'd really appreciate if someone could help me. Thanks :)
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cepheid
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#2
Oct9-04, 03:16 PM
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Hello!

My classmates at UBC did an "edible car" project for their first year. But I transferred into UBC in second year, so I can't help you at all! Maybe some mod should move this thread to "general engineering"...it might get more interest there? Just a thought.

You have not described the format of your competition, but from what you typed, I'm inferring that you and your colleagues will each build an unpowered car out of edible components and release them from rest from the same position at the top of a 30 degree incline. Whoever's car travels the farthest wins the race, right? I can see why the emphasis would be on distance, for it occurs to me that making freely/smoothly rotating wheels out of food would be a challenge! You don't want your wheel's gumming up, or having to grind out a bunch of crumbs just to keep moving! Unfortunately, I don't know what "cow tales" are, so I can't give you my opinion on that choice.

Some more thoughts:

-- I'm not sure whether the axle length affects the velocity attained. My instinct says not at all. What do you guys think?

-- "The heavier it is, the further it will go." Perhaps, but not due to gravity, right?! Isn't acceleration due to gravity independent of mass? It seems to me that the cars will have accelerated to the same velocity by the bottom of the ramp. (Galileo's alleged expmt?). However, the heavier cars may have more inertia, making them less susceptible to deceleration due to friction on the straightaway. I imagine this effect would be slight. And what happens if you make a monster car, only to find that it is slow getting started because it has to overcome a greater force of static friction? It's harder to predict what will happen than I thought. Maybe this is a pretty cool first year project after all, even if it is a waste of food (i'm assuming that you can't actually eat the edible cars at the end...they'll be dirty from the ramp during the race!).

--As for wheel *size*, how much effect do you think it would have in a free coast down a ramp? Again, my instinct says "none at all". My reasoning is that if two cars with differing wheels sizes accelerate at the same rate down the ramp, then at any point in time they've covered the same distance, it's just that the larger wheels have undergone fewer full rotations over that distance than the smaller ones. But again I direct it to PF: what do you guys think?

Edible car or not, make this a real physics and/or engineering project. List anymore factors that will affect its descent, model the motion of the car, do any calculations if you think that it's relevant. Perform as many tests as you can in the time you have. Good luck, and have fun!
Romperstomper
#3
Oct9-04, 05:26 PM
P: n/a
You should use paste for the adhesive. It's edible.

BobG
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#4
Oct9-04, 06:29 PM
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I need advice on how to make a car


You want as much dense mass as possible (do you have a weight limit?). Cepheid is right that the extra weight wouldn't make it accelerate faster, but it will have more momentum when it leaves the ramp. p=mv

You also want it streamlined so the air doesn't slow it's forward velocity as much, however a wide horizontal cross section would be an advantage, since the air would slow its descent (a wide wedge shaped car?)

You need axles that spin with as little friction as possible (on a pine car derby car, you lubricate the axles with graphite - you might have to use some kind of edible lubricant for your project)
TillEulenspiegel
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#5
Oct9-04, 07:57 PM
P: 66
Ahhh! BobG is correct , the body?
A wedge of the densest, driest cheese you can fing...Paramasan Romano etc.
the lubricant is something you want completely viscous at room temp...I say lite soy oil . The wheels? ...Cucumber slices that have been treated with a sprinkling of salt ( removes the moisture...less weight and solidifies the flesh ) . The axal Hmmm that depends on the intended definition of edible...I would look along the lines of a dried grape vine or similar. If wheel stops are an issue ( where the wheel cant slide or wobble ) I would think something on the order of dried fruit. HAHAHA I love cooking'
swati621621
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#6
Oct9-04, 08:10 PM
P: 2
yeah guys, I actually have to EAT it after I'm done, or I totally would have used paste :-p

Um..yea..haha I'm only in senior HIGHSCHOOL physics.. :-p so...haha yea, I'm kinda inexperienced

And thanks for the help :)
pervect
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#7
Oct9-04, 09:05 PM
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Quote Quote by swati621621
Hi there everyone,
For physics, I have to make a car entirely out of food. And, I'm really not sure how I should proceed.
Wow, that's a new one.

I dont' know if this idea is any good, but instead of making the wheels out of cookies, you could try ice cubes. In fact, you could make the whole car out of ice. At least three formats come to mind, "just a big slab", "concentrate the pressure", and even "make a big round wheel and/or big marble and let it roll". The last may be cheating a little, consult your contest rules.


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