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View Full Version : Mathy Help Question: Newtons/Pound Force/PSI Question



jpatterson
06-03-2013, 08:08 PM
Hello, I am looking for some info from anyone more well versed in this type of math and physics question. I know you cannot directly convert pressure and force from one to the other without extra information, but I have a set of values below and I'd like to get some info on what to do with it and how.



Weight (lbs)

Feet/Second

Sq In.

Newtons

PSI

?



1.5
23
3.4
1400




1.5
46
3.4
2800





A. A 3.4 square inch, 1.5 lb. object can travel either 23 or 46 feet per second, and will yield a force of either 1400 or 2800 Newtons, appropriate to the speed.

B. How do I get the PSI (pounds per square inch) for both speeds?

C. What is the "pound" measurement for force (not PSI), that is equivalent to Newtons, and how do I get it? Something like "foot pounds" or "pounds of force". I am not sure which is the correct term and formula if I wanted to find out how much "force" an object has when it impacts, this force being the "pound" version of Newtons.

D. Essentially I am looking for a contextual "bridge" for "converting force to pressure" (Newtons to PSI), using this particular case just so I can understand the proper steps, for like objects and measurements.

Thank you to anyone who reads this, and moreso to anyone that can actually help with it.

PS: i found some data on hailstones, from pea sized to CD sized, that range in pounds of force from less than 1 to 250 pounds (also listed it in joules), when falling from the sky, and I wondered how that compared to say, a punch or various other things.

nijineko
06-05-2013, 10:10 AM
would this (http://www.translatorscafe.com/cafe/units-converter/pressure/calculator/newton-per-square-meter-[N/m%5E2]-to-psi-[psi]/) or this (http://www.thecalculatorsite.com/conversions/pressure.php) help?

jpatterson
06-05-2013, 06:57 PM
I've been all over the net and have a lot of calculators and such bookmarked and they're useful to various extents. Never hurts to have another one, thanks Nijineko. =) I have someone in chat that has been helping teach me about the physics stuff too so that's been quite helpful.

nijineko
06-06-2013, 01:32 PM
um, do you not have the data you need? if you have newtons per square meter, then it's a pretty simple conversion to get psi with both of those calculators. am i missing something?

jpatterson
06-06-2013, 06:10 PM
It is more not knowing what I do need, which terms give what, and which formulas to use to get them. One of the bits of data I didn't have is the distance hail would travel, if I were doing that example, and how long it takes to do so - because of the varying densities of different weights, the time changes. So I'm looking at when those types of things become important and when they're generally a set matter.

nijineko
06-07-2013, 11:17 AM
i think it would be safe to assume critical velocity for most hail-like projectiles raining down naturally from the heavens.