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Dutchess_lll's avatar

If a piece of metal is 8 feet long what would the diameter be if it was bent into a circle?

Asked by Dutchess_lll (8753points) July 1st, 2019

As asked. I can’t recall the equation that would give me the answer off the top of my head.
I hit 8 / pi and came up with 2.5… ?

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23 Answers

stanleybmanly's avatar

You want the formula for the diameter (2r) if you have the circumference? If the formula for circumference is 2(pi)r, you simply do the algebra to determine r c=2(pi)r. Divide both sides of the equation by r and you have c/r=2(pi). Then divide both sides by r and you have c=2pi/r

seawulf575's avatar

Roughly 2.5 feet.

Dutchess_lll's avatar

I don’t have the circumference or thd diameter. All I have is a straight line that needs to be bent onto a circle.

Dutchess_lll's avatar

That’s what I came.up with too @seawulf575. :( not big enough.

ragingloli's avatar

about 90 Barleycorn.

Dutchess_lll's avatar

I see ya 90 barly corn an raise ya a bushel of sprouts!

canidmajor's avatar

The circumference is the length of the thing. It will still be as long whether straight or in a circle.
In this case, 8 feet.

Dutchess_lll's avatar

Guess I need to tie 2 together to get the diameter I want.

Brian1946's avatar

@Dutchess_lll

What diameter do you want?

stanleybmanly's avatar

You have the circumference, you want the diameter which is twice the radius (2r). As long you know any 2 of the 3 measurements, you can juggle the c=2(pi)r equation to determine the 3rd.

Dutchess_lll's avatar

I have an idea for a firepit guard Brian, to keep kids safe. Firepit sizes vary though so…IDK. At least 4 feet.

stanleybmanly's avatar

I looked at my first answer and it’s all fkd up. There’s an inadvertent r on the left side of the first equation.

Dutchess_lll's avatar

That’s ok StanlyMan! I had a Eureka moment….portable.do fencing! They come in different sizes.and they’d be a lot more stable than a circle.

Brian1946's avatar

@Dutchess_lll

Then the minimum length you need is 12’ 7”.

LuckyGuy's avatar

Multiply the diameter you want by Pi. if you want 5 ft, multiply by 3.14 to get 15.7 ft. 15 ft 8½ inches. Call it 16 ft. You’re not building pianos.
~Or convert it to Barleycorns.—> 563 barleycorns

Dutchess_lll's avatar

Loll @Luckyguy!

I think a portable dog fence is a better answer. It’s already made and more stable. Lot less expensive and a LOT less work.

Pinguidchance's avatar

Is it a circular dog fence, if yes what’s the diameter, if not what’s the perimeter?

Dutchess_lll's avatar

But it doesn’t have to be circular @Pinguidchance. I was stuck on that because firepits are circular. I’m finding octagonal dog fences with adjustable panels that might be the ticket. Have to wait till I get home to research down to the bone.
I just had a young mother damn near give her 2 year old a spiral fracture on the his arm last night when she finally got off her ass to yank him away from the fire.
Gotta come up with something.

Love_my_doggie's avatar

Just had it right at approximately 2.5, @Dutchess_lll

The formula is: C = 2(pi)(r), and we know that C = 8.

8 = 2(3.14)r
8 = 6.28r
1.27 = r

d = 2r
d = 2.54

Dutchess_lll's avatar

See guys…. it’s not even that complicated. Just 8 / 3.14. That’s all.
I’m not building a piano!

RocketGuy's avatar

You could say (more accurately) 2.546 ft, but the contractor would laugh at you.

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