Roll on the 20th June

[dirt diggler]

Hmm, well actually Graham was right but for the wrong reasons, and you are wrong but for the right reasons.

Friction is a function of contact FORCE, not SIZE. So if you increase the mass of a lever, you also increase the friction in the lever. Friction is independent of surface contact area.

Demo: get a table coaster (those little disks the little lady makes you set your beer on so there wont be rings on the table she just cleaned), add a second one on top. Pull it across the table, measuring the force required with a spring scale (make sure table is clean and free from dirt/debris). Redo the demo, but this time with coasters side-by-side. The mass is the same, but the surface area has doubled. You will find the force is exactly the same.

Now you ask "then why do race cars have wide tires to prevent slip?" Same reason I had you clear the table from dirt and debris. If there is sand, bits of gravel, etc between the road and the tires of a race car, this will reduce the coefficient of friction. Lets say for a moment the car has sand under 1" of its 12" wide tires. The sand has now jeopardized the contact friction of 1/12 of the tire. But by widening the tires, there is more contact surface and the portion decreases. For a 24" tire, now the jeopardized portion is only 1/24 of the total tire, decreasing the probability of slip.




We are in accord. I think there was a miscommunication somewhere though. I probably wasnt clear.

For a balanced lever (weights hanging, equal or unequal lengths), the torques would be the same and the lever would not move from horizontal. It would move if you rotated off horizontal as it would try to regain its balanced, level position. A balanced lever with weights on the center axis of the lever would not do this, which is what I meant by "it would move" as opposed to "float" at some angle. I was not suggesting a balanced, level lever would rotate simply because one was hanging lower, which is where I think the miscommunication occurred.

Also, considered two unbalanced levers, one with weights hanging equal distances and one with weights hanging unequal distances. When I said this "would produce a different effect due to unequal vertical shift contributions from each side," I was implying the two otherwise similar levers would have a different resting position.

-PurePower

Pure Power, Ummm  I don't see what this analogy has to do with my analogy.  I believe I clearly state that the heavier wheel would have more friction than the lighter wheel, but would also spin longer. it spins longer because of momentum.
now I haven't timed this to be exact but, I would think that two wheels of the same dimensions, but with one weighing twice as much, spun at the same RPM, would see the heavier wheel spin for almost twice as long. even though the friction is higher.
This was the point I was trying to make. 

[Rusty_Springs]

Pure Power, Ummm  I don't see what this analogy has to do with my analogy.  I believe I clearly state that the heavier wheel would have more friction than the lighter wheel, but would also spin longer. it spins longer because of momentum.
now I haven't timed this to be exact but, I would think that two wheels of the same dimensions, but with one weighing twice as much, spun at the same RPM, would see the heavier wheel spin for almost twice as long. even though the friction is higher.
This was the point I was trying to make. 

Hi Dirt
First this is good you have me thinking and I like that, second I would think the small weights friction is more then the big weights and not the other way.

Why do I think that because the surface to surface contact is the same but the air friction is more for the small weight because it orbits the big weight needing to cut through the air more causing more air friction.

I maybe wrong with that but thats how I see it.

Take Care Dirt
Graham

[dirt diggler]

Hi Rusty,
I'm not sure that I follow what you are saying about the air resistance.  if the two wheels are the same dimensions, air resistance should be the same. the only difference should be the friction in the bearing, which of coarse would be more on the heavier wheel. 
the way I see it mass gives us the power to overcome friction.

Dirt Diggler

[Rusty_Springs]

Hi All
This is all beside the point I said friction is your enemy, you maybe able to cut it down but you still have it to deal with.
Why I said it was because people seam to think its a non issue and its not its real and needs to be delt with.
Take Care All
Graham

[ramset]

WHERE IN BLAZES IS BATMAN     WITH THE 617 HP BATALATOR     MOVIES VIDS    LETS GO BATZILLA  Chet