Math help

Ah, the old slipsticks. Might still have mine in the basement somewhere.
If I tried to bend a pipe into a circle it would break.
 
bookworm - mind explaining how both flat ends would touch without getting a flat spot on the circle? A true circle will only have tangent points, never a straight spot, no matter how small.
 
HY: So where does the extra 1" of pipe for the OD come from??
 
half the diameter of the pipe (in his example 1") on both sides of the circle.
 
quote:
Originally posted by pdecat

Hummmm the pipe is 8' on all sides and the middle.

After you bend it into a circle the outside would have to be longer than 8' if the inside were still 8' and the pipe touches at all points so unless the pipe stretches or the inside compresses it must become flat. Inner diameter is
D=8'/pi

Click to expand...


correct.

G
 
I stand corrected. Unless the outside stretches, the inside edges will touch when it's rolled. Therefore the inside circumference will be 8' and there will be a gap at the outside circumference. I was mentally picturing bending exhaust system piping, which stretches in the roller. Mathematically, without any stretch, the inner corners would touch and the gap would form a "V". Brain freeze; sorry. Hy
 
hey...no apologies...just thought maybe I was missing something. Which wouldn't be a surprise!!
 
Funny, just showed my grandson a new fangled device that I used to pass a statistics course back in 1964. No batteries, no internet or electrical connection. Move the middle, slide the plastic piece and look at the answer. Then I took out my wife's portable electric typewriter and showed him how it does the work of both a computer and a printer with instantaneous gratification. Now if I can only find that damn carbon paper!

Gene
 
My slide rule is my shepard, I shall not want/ Yea though I walk through the valley of pop quizzes I shall have no fear, for my slide rule shall prepare for me the correct answer. and so forth and so forth untilthe end.

G
 
I read by putting sand in the pipe will prevent it from crimping no flat spots. I'm glad my question got so many interesting responses
 
Is this "real" math or that new "Common Core" 3x4=11 crap?
 
Back to the problem - GetaKey got it, Diameter = Circumference / pi (3.14).
 
Google solves equations very well including exponents,rots, logs etc. realt amazing
 
Unless u are an investor no can tell....hopefully will bring to market within next few months. I have an great idea and a prototype is constructed and tested and all the other admin stuff done. Then will tell and hopefully people will buy it.
 
Brian - Would you mind making an extra one for me? I need a new round tuit, as my old one broke long ago and I still haven't fixed it. 8' inside circumference and 30.557749073643904" (push button slide rule) inside diameter should be just about right for it. Thanks! If you are just making a piping plover corral, nevermind.

http://www.onlineconversion.com/circlesolve.htm

(I don't miss my old slide rules or leaky fountain pens at all.)
 
Maybe more than you need to know, but the diameter of the circle can depend on more than just the math. How important is it to know the diameter with accuracy.
The pipe diameter and the strength of the materials can also end up in the calculation.
If the tube is very small diameter, the diameter from just the straight math would be quite accurate for the center-line of the pipe because the stress and deformation is not significant.

As the diameter of the pipe increases, the bending into a circle causes bending stresses and elongation on the outside and compression on the inside of the circle radius. For some materials and diameters the elongation on the tensile side may be different than the compression on the inside of the circle.
I suspect this would give a slightly larger diameter circle
 
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