SANDPAPER

Lemme see ... I'd say the hard, sharp edges, or facets, of the abrasive bonded to the paper substrate, or backin', score the surface of a less-hard material against which the abrasive material applied, separating fragments of that surface's material from the body of that less-hard material much as might tiny knives or chisels.

Depending on factors such as relative motion of abrasive and less-hard material, and the pressure forcin' the abrasive against the less-hard material, the action may vary from deep, agressive material removal to fine polishin'.

The abrasive itself will be dulled, worn away, and separated from its supportin' substrate, or backin', renderin' the abrasive construct less and less effective over a period of use.

An abrasive applied to a surface either suspended in a liquid or popelled by gaseous pressure will have a similar effect.

There. I think that's about got it. Will that do it for ya?

THANX
Thankyou for that... That really helped..
Do you know anything about the differences between.....
Dynamic and Static Friction.. I am only in year 8 so if you wouldnt mind explain simplyl..... Thanx.............YOURE SMART

Yeah, sorta - dynamic friction would be more or less friction due to the motion of one surface relative to another, whereas static friction would be more a function of the overall mass (think gravity here) or pressure (think independent mechanical force here) component of one surface relative to another surface to which the first surface is applied. Another thing about friction; if motion and friction exist together, heat is a concommitant byproduct of the interaction. A relatively low pressure applied with a relatively high motion component (think speed or velocity) can result in comparatively high friction-generated heat, while relatively higher pressure (think weight or mechanical force) applied with relatively less motion can generate comparatively high heat. That all has to do with the laws of thermodynamics. Friction is what keeps your car on the pavement, what turns meteorites into bright streaks in the sky, and what turns peat into coal and coal into diamonds.


G'nite, now; the movie I was watchin' is over, its almost 2:30 AM here, and I'm goin' to bed.

Oh, and welcome 2 A2K - hope ya enjoy your visit, and hope ya decided to drop in on a rgular basis. Lots to look at around here. Look the place over; no tellin' what ya might find.

tahnz
is their any possible way you can make that sound simple.. i am only in year 8...... plz anything that is kinda basic

Perhaps an example will help. Suppose you are standing on a slippery ramp, but you don't slide, as long as you don't wiggle even a little. That is static friction that is keeping you from sliding. If the slope is 30 degrees and you weigh 50 kilograms, the friction is 0.5 times 50 = 25 kilograms. The slightest wiggle and you start to slide. Typically the sliding friction = dynamic friction is less than the static friction, perhaps 10 kilograms so you gain speed rapidly as you slide down the ramp. If the dynamic friction had been 24 kilograms you would gain speed slowly as you slid down the ramp. Neil

thanx alot.....it really helped to understand