What effect does weight have on grip?

[jbot]

Magdor strikes again

[magley64]

*edit* In theory. In practice, the weight distribution of the phone book will change the separation force, but it still has nothing to do with surface area.

So what's the reason for the profound difference in separation force from 5 pages to 1000 pages if the clamping force remains constant?

[OsuMj]

You're asking why it takes less force to move 5 objects compared to 1000 objects?  ... think about what you're asking here.

I know you're super certain that surface area has something to do with it, but I can promise you that smarter people than us have spent hundreds of years figuring out that it doesn't.  Before I spend any more time trying to convince you of this - Please google Amonton's 2nd law - then if you are as smart as you think you are, you'll be able to read a page or two and figure this all out for yourself.

Edited August 12, 2014 by OsuMj

[magley64]

You're asking why it takes more force to move 5 objects compared to 1000 objects? ... think about what you're asking here.

They're the same phone books, in one case you interlace 5 pages, and clamp the books together. In the other case you interlace 1000 pages and clamp with the same force. The surface area is the only thing we're changing.

It's because the pages aren't ideal smooth planar surfaces and neither are roads.

Edited August 12, 2014 by magley64

[OsuMj]

Ok. I've decided that I'm not going to argue this with you for the following reasons

1. OP has already been addressed

2.You won't take the simple steps to understanding the topic so you don't sound like an idiot while discussing it despite being told the exact words to look up.

3. I'm not a physics teacher

4. I actually don't care whether you get it or not

[magley64]

I get it, but we're not dealing with a vacuum, we're not on some ideal planar surface. I've taken the courses and understand the math, what I'm saying is that there are erroneous inputs that aren't taken into account in the equations, inputs that are dependent upon surface area.

[fizzer]

I get it, but we're not dealing with a vacuum, we're not on some ideal planar surface. I've taken the courses and understand the math, what I'm saying is that there are erroneous inputs that aren't taken into account in the equations, inputs that are dependent upon surface area.

The problem is I don't think you do understand the math. The equations have stood the test of time because they work, at least to a first order approximation(with exceptions for "sticky" surfaces and a few others). Any non-standard contribution is likely to be very small in comparison to the magnitude of the major factors at play. I'm also not going to bother trying to argue with you, but in the phone book situation if you don't understand how an increase by two orders of magnitude of interacting surfaces in addition to a normal force which now scales as you pull harder on the books (think about the angles each page is at with respect to the pulling forces) can explain the "impressiveness" of the trick, then I'm out.

[magley64]

The problem is I don't think you do understand the math. The equations have stood the test of time because they work, at least to a first order approximation(with exceptions for "sticky" surfaces and a few others). Any non-standard contribution is likely to be very small in comparison to the magnitude of the major factors at play. I'm also not going to bother trying to argue with you, but in the phone book situation if you don't understand how an increase by two orders of magnitude of interacting surfaces in addition to a normal force which now scales as you pull harder on the books (think about the angles each page is at with respect to the pulling forces) can explain the "impressiveness" of the trick, then I'm out.

And those "exceptions" are exactly what I'm talking about. Thank you for finally agreeing with me that there are real world instances where surface area has an effect, to varying degrees given the specific application. Velcro, another perfect example. Adhesives, oh boy, sometimes adhesives are made from rubber, like tires, could there be some overlap there? Hmm

Edited August 12, 2014 by magley64

[jbot]

[CBBaron]

One reason heavier motorcycles have wider tires is that motorcycles have pneumatic tires. Which means they are full of air and flex under load. The contact patch of a tire is basically the load/pressure. So at the same pressures a heavier vehicle needs a wider tire or higher pressure. Since higher pressure requires stronger tires and a harsher ride the easier solution is a wider tire.

 

In addition the heavier vehicle will put more stresses on the tire wearing out the rubber faster. If this is spread over a larger area then the wear is reduced and the tire lasts longer.

 

Craig