Abe Froman

Correlation between radius and diameter, help please.

https://lemmy.world/post/4022107

Correlation between radius and diameter, help please. - Lemmy.world

I recently discovered I could split a piece of 4 inch PVC pipe lengthwise heat it up with a heat gun then weight the pvc between some sheets of plywood and end up with a flat PVC sheet. This was a revelation to me as I am a tinkerer and have sourced pieces of plastic from other sources for years. Once I split the 4 inch pipe up the middle and flattened it I measured it and realised it was exactly 13 inches. I left school 20 years ago and I do realise there is a direct correlation between radius and diameter but I was never very good at mathematics. I currently have a sheet of rubber on my workbench to protect the surface but I think the pvc sheet would be great to protect it if it was big enough. My workbench currently measures just over 24 inches. What diameter of pipe would I need to create a PVC protective top for my work bench. I’m in UK if that helps. There are standard sizes of 4,6,8,10 inches of PVC pipe available from what I can see. I am no Mathematician so any help is greatly appreciated.

Aug 28, 2023 at 7:14pmWeb
Show threadAbe FromanAug 28, 2023

Many thanks. I can remember this from school but that is so far away from me now. Trying to remember practical applications from what I learned and the other stuff I was taught that has no real applications is a bit much.

Thanks Lemmy.

Show threadbeaubbeAug 28, 2023
The whole pipe will have a circumpherence 3.14x the diameter of the tube. Obviously being in the real world, it won’t be perfect as the plastic will stretch and contract with heat and pressure but 3x is a good ballpark. The mathematical relation is PI (3.14159…)
Show threaddmention7Aug 28, 2023

You’re thinking of circumference (distance around), not radius (distance from the center)

Circumference is pi * diameter. The circumference is also what you get when you cut the circle in half and flatten it.

Pi is approximately 3.14, so your flat sheet will be a little more than 3x the diameter.

Show threadRouxibeauAug 28, 2023
You failed to define diameter. diameter is the distance across, or two times the radius.
Show threadGandarfDeGrapeAug 28, 2023

Radius is the length of the middle of a circle to the edge (2")

Diameter is the full width of the circle (4")

Circumference is the length of the circle itself were you to cut and unwind it. Circ is calculated via: pi * diameter

So, If you’re wanted 24 inch Circumference, it would be 24 ÷ pi which is 7.639437268.

So a 8+ inch diameter is what youd want.

Show threadCaptnkrk69Aug 28, 2023

To get the flat length of a circle multiply it by pi(3.1415). The diamtere is the length from one side of a circle to the other. A radius is length of a circles size from center to outer edge. A radius is half the size of a diameter.

pi definition

Pi - Wikipedia

Show threadMoobythegoldensockAug 28, 2023

You mean correlation between diameter and circumference? Circumference = diameter x pi

So for your problem, we have 24 = pi*d

d = 7.639…

So an 8 inch pipe should cover your whole work bench, with a small amount of overhang on the edges.

Show threadBluetreefrogAug 28, 2023
OP, friendly mod reminder that posts should end with a “?”.
Show threadBen Hur Horse RaceAug 29, 2023
good job, officer
Show threadChickenstalkerAug 29, 2023

> heating PVC

Do it outside and wear a gas mask. Don’t breathe that shit. Dioxins.