Topic awaiting preservation: Ft.LBS = Weight ??

Is there any relationshop between the two? I'll try to explain.

I have a piece of foam rubber and want to see how it it stands up to 200 lbs of constant weight over a 7 day period. I don't have a 200 lb weight handy but I do have a torque wrench, and can easily sandwich the foam between whatever and torque it down but what, if any, relationship is there between torque and weight. How many foot pounds?

Clear as mud huh? =)

You're straaaaaaaaaaange...

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Pressure - An external force applied over some area. Expressed in force per area unit (P=F/A). For example, let's say there is a one foot cube that weighs 200 pounds sitting on the driveway at your house. How much pressure is the box exerting on your driveway? P=F/A Therefore, Pressure = 200 pounds divided by an area of 1 square foot (one times one - the surface of the box in contact with the ground). The answer is 200 psf (pounds per square foot).

Try looking here for your answer

http://mathforum.org/dr.math/faq/

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Webbing; the stuff that sticks to your face.

You need to know by how much your foam rubber stretches for every pound of weight applied to it. I dont know much about foam rubber, but springs have something called 'spring constant' which is measured in Newtons per Meter, that is how much force you need to apply to stretch the string by one meter. I suppose something like that exists for your foamrubber, and I guess the only way to find out is to either experiment or contact the manufacturer. Also keep in mind, that after some threshold, you need more force to stretch it a bit more. In other words, this constant isnt really a constnat.

Ah, yes- the variable constants - always make it more difficult to figure out... sometimes

that math site was a lot of fun

shhh, people will think we are nerds.

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Webbing; the stuff that sticks to your face.

Thanx ppl. I came up with something of a workable solution and I realize now my question was a bit misleading.

A 'compression' test I guess would have been a better approach. Not what might be called a 'stretch' test. The material is a neoprene used for 'wetsuits.'

So my solution: A bathroom scale under one leg of a heavy 'sideboard'... that weighed in at 125 lbs. Removed the scale put the neoprene under that leg... weighed out 50 more pounds of stuff that included a 30 lb bag of rice and a couple of cement blocks which I then placed on the corner of the sideboard. So I figure there's close to 175 pounds pressing down on the neoprene. In a week...maybe sooner I'll know if the neoprene remains compressed or returns to something close to its orginal thickness.

Yup I'm nuts. =)

Almost forgot... the math page is great. Under the classics... the bellboy missing dollar bit.. I used not so long ago to drive a few people crazy... hope they don't find that page. =)

(Edited by NoJive on 11-26-2004 09:44)

Love the maths site
I love maths but soon found some problem examples on that site that I didn't even know were problems 'til now!

NoJive,

Did you put something between the leg of the sideboard and the neoprene. The weight of the sideboard and the stuff on it was distributed over the area of the scale when you weighed it. When you took out the scale, you are now concentrating the weight over the (presumably smaller) area of the foot of the leg. This will change the amount of pressure applied to the neoprene. You need to be measuring the pressure you are applying in pounds per square inch.

I think the bathroom scale will give you a (more-or-less) accurate measure of the amount of weight you are applying. If the foot of the sideboard has an area of 2 square inches, you are only applying about 80 pounds per square inch to the neoprene. If you are trying to test to 200 pounds per square inch, you need to reduce the contact area between the sideboard leg and the neoprene, or add a lot more weight to the sideboard.

-- not necessarily stoned... just beautiful.