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wwilliam54
 
Quote:
Originally Posted by boshi View Post
I see. I never argue that it is unimportant, I just think it's really funny when people try to drop terms to impress people.

Oh shits multivariable calculus! Diffeqs! O gnoes!

lol
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Old 01-15-2007, 09:46 PM wwilliam54 is offline  
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Rang3find3r
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Well, this thread is now getting really interesting... And I have to give credit to a good friend of mine for this link, but most of you are in fact WRONG

http://yn.la.ca.us/nsrc/sci/sci023.html#anchor1261941

Summary:

Quote:
I. STATEMENT OF PURPOSE AND HYPOTHESIS:

We would like to do a scientific research project to determine
the effect of weight on the speed of objects rolling down an
inclined plane. Our hypothesis states that objects of
different weight and same shape will roll down an inclined
plane at the same speed.

II. METHODOLOGY:

First, we wrote our statement of purpose and our review of the
literature. Then we developed our hypothesis. Next, we wrote
our methodology to test our hypothesis. Then we made a list of
materials. The materials we used were two small condensed milk
cans. We emptied one of the milk cans and it weighed 1.92 oz.
The other milk can that was full and weighed 2.16 oz. We also
used two medium sized coke cans. We did the same procedure
that we did with the condensed milk cans. The empty coke can
weighed .48 oz. The full one weighed 13.76 oz. We then used
two large juice cans that weighed 58.8 oz. full and 5.60 oz.
empty. Our last piece of material was the plywood used for the
plane. We created a data collection form and observation
sheet. Then, we took the empty condensed milk can that weighed
1.92 oz. and the full condensed milk can that weighed 2.16 oz.
and rolled them down the inclined plane and observed which one
hit the ground first. We repeated this procedure for a total
of 6 times. Then we took the coke cans and did the same thing
as we did with the condensed milk can. We repeated the
procedure for a total of 6 times. Then we took the juice cans
and did the same procedure. We repeated it for a total of 6
times. When we finished, we put the information on our
observation form. Then we analyzed our data with charts,
statistics, and graphs. Next, we accepted or rejected our
hypothesis and wrote our summary and conclusion. We then,
applied our findings to the real world.

III. ANALYSIS OF DATA:

The results of our experiment show that all of the heavier
objects reached the ground first when rolled down an inclined
plane. The heavier the object was the faster it rolled.
Friction slowed the lighter objects down more than the heavier
objects because the heavier object had more mass and was able
to overcome the resistance of friction better.

IV. SUMMARY AND CONCLUSION:

For our six trials with each of the cans, the heavier cans hit
the ground first. Therefore we reject our hypothesis which
stated that objects of different weights and same shape will
roll down an inclined plane at the same speed.

V. APPLICATION:

When kids make Pine Box Derby cars they should make their cars
heavier so that they will roll downhill faster.
To answer my own question, which NONE of you were able to satisfactorily answer on your own, yes, the additional weight of my vehicle DOES give me an advantage when going down hill.

This advantage does not mean that I will always out accelerate every other lighter vehicle down hill of course, but just as I am at a disadvantage when going uphill, due to my added weight, I am at an advantage down hill, due to my added weight.

Think about it this way: Try to push two cars up a normal driveway - One a lightweight 2000 pound whatever, the other my 4500 pound Bonneville. Well my own experience has shown to me that I can easily push lighter vehicles up my driveway by myself, but attempting to push my car up my driveway by myself is totally impossible. Why? The extra weight of my car is pushing back at me with far more force than the lower weight of the smaller vehicle. Simple physics. It stands to reason that this stronger force pushing back at me(due to the heavier weight) will result in faster acceleration for the heavier car.

This thread was interesting, but most of you were in fact wrong. Seems that all the education in the world is not a replacement for common sense.

I'll consider this thread a success, and my car a down hill champion
Old 01-15-2007, 10:56 PM Rang3find3r is offline  
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well, there is an issue with that: the farther out the mass is, the more rotational inertia an object has, and therefore the slower it will roll down a hill. another way you could do an experiment like you did:

take a toy car and roll it down a hill. time it, record time.
take two toy cars and attach them side by side. roll them down the hill. time it, record time.

the two times should be equal.

as for heavier vehicles, it depends on where the weight is. if the wheels on two cars are the same but one is heavier, it will roll down the hill faster than the other. there are plenty of other things that will effect it too.
Old 01-15-2007, 11:04 PM Junkie Mod is offline  
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wwilliam54
 
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Originally Posted by Junkie Mod View Post
well, there is an issue with that: the farther out the mass is, the more rotational inertia an object has, and therefore the slower it will roll down a hill. another way you could do an experiment like you did:

take a toy car and roll it down a hill. time it, record time.
take two toy cars and attach them side by side. roll them down the hill. time it, record time.

the two times should be equal.

as for heavier vehicles, it depends on where the weight is. if the wheels on two cars are the same but one is heavier, it will roll down the hill faster than the other. there are plenty of other things that will effect it too.

yup
rotational inertia != linear momentum
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Old 01-15-2007, 11:07 PM wwilliam54 is offline  
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Quote:
Originally Posted by Junkie Mod View Post
well, there is an issue with that: the farther out the mass is, the more rotational inertia an object has, and therefore the slower it will roll down a hill. another way you could do an experiment like you did:

take a toy car and roll it down a hill. time it, record time.
take two toy cars and attach them side by side. roll them down the hill. time it, record time.

the two times should be equal.

as for heavier vehicles, it depends on where the weight is. if the wheels on two cars are the same but one is heavier, it will roll down the hill faster than the other. there are plenty of other things that will effect it too.

Exactly.

rang3 forgot that rotating mass =/= mass with wheels

That 3rd grade experiment with rolling cans down a ramp is cool and all but has little to do with two cars racing, using their own motor for propulsion.

Rang3, I'm sad I knew you could wrench but I figured you were a quick draw with this common sense stuff too.
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Old 01-15-2007, 11:10 PM [H]ard|On is offline  
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Quote:
Originally Posted by [H]ard|On View Post
Exactly.

rang3 forgot that rotating mass =/= mass with wheels

That 3rd grade experiment with rolling cans down a ramp is cool and all but has little to do with two cars racing, using their own motor for propulsion.

Rang3, I'm sad I knew you could wrench but I figured you were a quick draw with this common sense stuff too.

sorry bub, you got this one wrong(edit: talking to you hardon):

(22:58:24) totensiebush: well, for the cans it's a whole different issue
(22:58:34) lockandb7: not really
(22:58:40) totensiebush: the farther out the mass is, the slower it rolls
(22:58:58) totensiebush: so a full can and an empty can made of really heavy metal won't go down at the same rate
(22:59:15) lockandb7: the actual human beings I spoke with about it today all agreed with me that yes, rolling down hill is different than dropping stuff... galileo's theory does not apply when you're talking down hill
(23:00:03) totensiebush: well, as another way to think about it
(23:00:15) totensiebush: take a toy car and let it roll down the hill
(23:00:32) totensiebush: now, take two of them, attach them together side by side, and let them roll down the hill
(23:00:39) totensiebush: will they take different amounts of time?
(23:00:49) lockandb7: presumably
(23:01:13) totensiebush: so being right next to another car rolling down the hill changes something somehow?
(23:02:19) lockandb7: well in theory no, actually there's no reason why it would be any different, because you've doubled the weight, but also doubled the number of wheels and every other possible factor..
(23:02:29) lockandb7: can't see how that's relevant though
(23:02:51) totensiebush: im saying that just because it's heavier doesnt mean it rolls down the hill faster
(23:02:59) lockandb7: but that's not correct
(23:04:05) totensiebush: ?
(23:04:46) lockandb7: why does one soda can roll down hill faster than the other? same diameter, same aerodynamics.. the heavier can is certainly encountering more friction, and yet it rolls down faster
(23:05:04) totensiebush: rotational inertia
(23:05:14) totensiebush: the farther out the weight is, the slower it rolls
(23:05:26) totensiebush: a better example would be a soda can made of steel vs one made of aluminum
(23:05:31) lockandb7: objects at rest tend to stay at rest.. inertia... it requires more force to get a mass moving than mass half the size
(23:05:34) lockandb7: where'd it come from?
(23:05:41) totensiebush: well
(23:06:00) totensiebush: im sure you'll understand that on a wheel, the farther out the weight is the harder it is to turn it
(23:06:01) totensiebush: right?
(23:06:07) lockandb7: absolutely
(23:06:24) totensiebush: well, the empty can has the weight farther out than the full can
(23:06:34) totensiebush: it may also have less weight, but the weight it has is farther out
(23:06:35) lockandb7: how on earth can you make that assumption?
(23:06:58) lockandb7: even if we assume that the water does not rotate with the can, they would have the exact same rotational inertia
(23:07:19) totensiebush: that's if the water does not rotate with the can
(23:07:19) lockandb7: if we assume that the water rolls with the can, the water filled can will have far greater rotational inertia
(23:07:33) totensiebush: yes, but what we need to look at is rotational inertia/mass
(23:07:39) lockandb7:
(23:07:43) lockandb7: that's what we're looking at
(23:07:58) totensiebush: why would it be higher on the water filled can?
(23:08:13) lockandb7: the can is a constant.. the same exact can vs. the same exact can.. adding water only adds inertia, both rotational and non rotational
(23:08:31) lockandb7: it woudn't, it would be the same, as the water would most likely not roll with the can
(23:08:34) lockandb7: it would be the exact same
(23:08:43) totensiebush: well, some of the water will roll with the can
(23:08:51) lockandb7: then you're only adding rotational inertia
(23:09:06) lockandb7: it is completely impossible for the empty can to have more rotational inertia
(23:09:14) lockandb7: totally, absolutely impossible
(23:09:20) totensiebush: as i said, rotational inertia/mass is what matters
(23:09:48) lockandb7: then why does the heavier can roll down hill faster?
(23:09:53) lockandb7: you've confused yourself I think
(23:10:10) totensiebush: meh
(23:10:13) totensiebush: i dunno
(23:10:15) lockandb7: lol
(23:10:24) totensiebush: it also depends on how far they let it roll
(23:10:33) totensiebush: if only a couple feet, air resistance won't matter much
(23:10:37) totensiebush: if its a long way it might
(23:10:57) lockandb7: yes, air resistance will only hold back the object with less mass behind it
Old 01-15-2007, 11:12 PM Rang3find3r is offline  
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wwilliam54
 
your still wrong, those cans dont go the same speed due to rotational inertia
a better test would be an inclined air table and blocks of different masses
5$ says I know what would happen
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Old 01-15-2007, 11:15 PM wwilliam54 is offline  
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Quote:
Originally Posted by Dumbfuck View Post
your still wrong, those cans dont go the same speed due to rotational inertia
a better test would be an inclined air table and blocks of different masses
5$ says I know what would happen

I am not wrong, nobody has proven one single thing, nor provided one single piece of contrary evidence. I was in fact absolutely correct in my initial thoughts, and the more research I do into the matter, the more it is made clear.

and what are you even arguing... they don't go the same speed because one has a large amount more mass that gravity is pulling on, and that additional force is what creates faster acceleration.

how do mag-lev trains work? how do they increase the speed of the trains? faster and faster? find yourself the answers to these and the physics behind it and you'll have your answer here as well.

the more force you apply to something, the more result you get. for every action, there is an equal and opposite reaction. you pull harder on something, it will move faster. how is this situation any different?

Last edited by Rang3find3r; 01-15-2007 at 11:21 PM..
Old 01-15-2007, 11:18 PM Rang3find3r is offline  
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Quote:
Originally Posted by I <3 EFI CARB SUCKS View Post
sorry bub, you got this one wrong(edit: talking to you hardon):

(22:58:24) totensiebush: well, for the cans it's a whole different issue
(22:5

...


t, air resistance won't matter much
(23:10:37) totensiebush: if its a long way it might
(23:10:57) lockandb7: yes, air resistance will only hold back the object with less mass behind it


Wanna help me out and tell me where I'm wrong? I'm sure as hell not reading all that, but it looks like he told you the same thing that we all did.

Also no shit you can't push your bonnie up your driveway, it weighs more. That's the whole inertia thing. You need to overcome it going up hill, down hill or flat. The power of your motor does that, but in the case of downhill you have gravity helping you. Since it helps both of you equally, it's a moot point.
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Old 01-15-2007, 11:18 PM [H]ard|On is offline  
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wwilliam54
 
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I am not wrong, nobody has proven one single thing, nor provided one single piece of contrary evidence. I was in fact absolutely correct in my initial thoughts, and the more research I do into the matter, the more it is made clear.

Galileo Galilei did
500 years ago
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Old 01-15-2007, 11:20 PM wwilliam54 is offline  
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Quote:
Originally Posted by Dumbfuck View Post
Galileo Galilei did
500 years ago

so you can't prove it then... next!

we're not talking about dropping objects from a plane. explain to me why the can rolled down the hill faster. we've eliminated rotational inertia, because if anything, the filled can has more of it. why then does it accelerate faster? more friction with the road surface to overcome, same air resistance, same rolling diameter, only more weight. why does it accelerate faster? galileo wants the answer to this, not his only marginally relevant theory quoted.

can you provide the answer to that or not?
Old 01-15-2007, 11:27 PM Rang3find3r is offline  
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Quote:
Originally Posted by Dumbfuck View Post
Galileo Galilei did
500 years ago

I'm starting to see why you guys give him a hard time in other threads 'pre-emtively'
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Old 01-15-2007, 11:27 PM [H]ard|On is offline  
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Quote:
Originally Posted by I <3 EFI CARB SUCKS View Post
so you can't prove it then... next!

we're not talking about dropping objects from a plane. explain to me why the can rolled down the hill faster. we've eliminated rotational inertia, because if anything, the filled can has more of it. why then does it accelerate faster? more friction with the road surface to overcome, same air resistance, same rolling diameter, only more weight. why does it accelerate faster? galileo wants the answer to this, not his only marginally relevant theory quoted.

can you provide the answer to that or not?

You're missing the point.

The only 'rotational' inertia in your bonnie would be your wheels. The rest is resting weight. Your car is not a giant can, now is it? Does it roll over itself repeatedly during this race? No

Look, do some small scale testing. Get a ramp, and roll some shit down it. Beer cans, smaller tomato paste cans, etc. Observe and record.

Now go get your favorite model cars out and repeat. You'll see a difference. The cans were affected not only by their weight, but also by their diameter since that weight had to be moved a greater distance every rotation. With a weight that has wheels (like your car) that doesn't matter.

Seriously go roll a hot wheels down a ramp. Then tape a shit load of pennies to it or something and repeat. Time each run and get back to us!
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Old 01-15-2007, 11:31 PM [H]ard|On is offline  
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The car with the LS7 will win the race.









I have no real contribution to the thread
Old 01-15-2007, 11:32 PM 4byTacoma is offline  
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Quote:
Originally Posted by [H]ard|On View Post
You're missing the point.

The only 'rotational' inertia in your bonnie would be your wheels. The rest is resting weight. Your car is not a giant can, now is it? Does it roll over itself repeatedly during this race? No

Look, do some small scale testing. Get a ramp, and roll some shit down it. Beer cans, smaller tomato paste cans, etc. Observe and record.

Now go get your favorite model cars out and repeat. You'll see a difference. The cans were affected not only by their weight, but also by their diameter since that weight had to be moved a greater distance every rotation. With a weight that has wheels (like your car) that doesn't matter.

Seriously go roll a hot wheels down a ramp. Then tape a shit load of pennies to it or something and repeat. Time each run and get back to us!


how do you not see these experiments as the same? the empty cam vs. filled can is the same experiment as a bare hot wheels and a loaded hot wheels. the water in the can does not rotate with the can(fill a clear two liter bottle with water and just as you're about to roll it down the hill, drip some food coloring in it - cap it and roll it, magic, the water doesn't rotate!). the rotational mass doesn't change, so it's the same experiment as with hot wheels cars.

one vessel has more mass, but the same aerodynamic properties(IE same wind resistance), the same rotational diameter(same size can), and the heavier can rolls down faster. how hard is this to understand?

my car has very little rotational mass compared to non-rotational mass, obviously. and? what does an empty alumimum can weigh? a small fraction of an ounce? filled it weighs 12 ounces, so it has many many times the non-rotational mass. well look at my car - a good couple hundred pounds of rotational mass(wheels, tires, hubcaps, brake rotors and drums, hubs, rear axles, outer half of the bearing races, lug nuts, etc. then a few thousand in non-rotational weight. again, many times the rotational, but the comparison between my car and the can is a lot closer than you would perhaps like to think.
Old 01-15-2007, 11:38 PM Rang3find3r is offline  
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