Formula needed for displacement

[Andrew Walsh]

How do you calculate the displacement of a cylinder 22 inches long with a circumference of 12.5 inches.

[Dan Major]

Andrew Walsh nomail wrote in news: [e-mail]:

Well, the circumference is 2 * pi * radius, and the volume is pi * radius * radius * height you do the math.

BTW - how do you remember the value of pi? Wow, I need a drink, alcoholic of course! (count the number of letters in each word)

[Unquestionably Confused]

on 8/4/2005 3:55 PM Andrew Walsh nomail said the following:

The volume of a cylinder equals the (area of the base)*height = ? r2 h

I'm not going to do all the math for you but determine the radius the easy way (measure or it) or extrapolate it from the circumference and go. I'd just use 3.14 for pi and let it go at that.

[George]

Pi r squared H is the formula for a cylinder. 3.1416*3.9788*3.9788*22 =

1094?

[Swingman]

First find the radius of the base with:

diameter = circumference/?

Then divide the diameter by 2 to get the radius, then plug in below

Then use the area of the base (? r2 ) times the height of the cylinder to get the volume:

V = (? r2) (h)

[Swingman]

Sorry ... my characters screwed up: ? is "pi" ... (use 3.14 for pi and you'll be close enough).

[George]

oops. 12.5 / 3.14 = 3.9788 which should be divided by two to give radius.

273.5

[gfretwell]

Volume of a cylinder is pi R squared x height. R= C/pi/2

12,5 circumference is a circle with a radius of 1.99 squared is 3.96 times 3,14 is 12.43

Hey is this a trick question ;-)

times 22 is around 273 cu/in

I suppose if you solved it algibraically you would skip a few steps.

[LRod]

Well, the area of the circle describing the cylinder is pi*r^2, so to find r we must first determine the diameter by dividing the circumference by pi :

12.5"/pi = 3.97899" (diameter)

The radius then is 3.97899/2 = 1.989"

Then we find the area of the circle described by the cylinder as pi * r^2

1.989^2 = 3.958 3.958 * pi = 12.434 in^2

Every linear inch of the length of that cylinder then is 12.434 in^3, so the cylinder volume is 273.555 in^3

However, displacement perhaps isn't the right word. Most often when discussing a cylinder, displacement means how much volume is displaced when a piston is moved in it, which is a function of the stroke of the piston, not the length of the cylinder.

Or, displacement could also mean how much water is displaced when a cylinder of the size described is placed in it, but that's a function of the weight of the cylinder in addition to the volume and can't be easily determined with the information given.

Which all means I might have missed the point of the question entirely.

[Duane Bozarth]

V = pi*r^2*h

[Andrew Walsh]

That's easy. Now if I just knew what V was, and r, and h I would have this solved.:)

Thank God some of the other answers were a bit less cryptic.

[Duane Bozarth]

Well, if you can't even figure out that the volume is a functionof the radius and height, I think there's no hope... :(

[JoeTaxpayer]

How I wish I could determine pi Eureka! cried the great inventor Christmas pudding, Christmas pie is the problem's very centre.

[Guess who]

C = 2Pi*R so R = C/(2Pi)

A = Pi*R^2 = PI * (C/2*Pi)^2 = (C^2) / (4Pi)

V = Ah = (C^2)*h/(4Pi)

Stick in the numbers and calculate.

Method 2: Find a graduated cylinder large enough [or make one] and drop it into some water and measure the increase in volume.

[Steve DeMars]

For the finest conversion program in the world, you can't beat Prokon. Try it for free, if you like it $20.00 is not bad . . .

[John DeBoo]

Pi are squared? No, pi are round, cornbread are square!

[Wood Butcher]

If you have a 4 function calculator - Take the 1st 3 odd digits and double them up thusly - 113355 Then divide thusly: ____

113|355 The ascii art is probably not going to show correctly but should show 113 divided into 355.

The result is correct to 0.00000027, or about 0.1PPM.

Art

[Larry Jaques]

Turn to page 355 of Lee Valley's Handyman-In-Your-Pocket reference book, Andy, old chap. V = (1/6) pi D3 = 0.5235988 x D-cubed.

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[Edwin Pawlowski]

Nothing cryptic about if for 7th or 8th grade math students. Ok, a hint, V = volume. Just think about what the others may be and you can solve it.

[Lew Hodgett]

Get a third grade math book, then read and understand it.

Lew