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)
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.
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 = π 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.
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)
Volume of a cylinder is pi R squared x height.
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.
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
Although I grant I made the (perhaps rash) assumption that you could
somehow muddle through to find the radius of a circle knowing the
If that's the root of the problem, then since c = pi*d = 2*pi*r ==> r c/(2*pi)
From which it follows that
V = pi*[c/(2*pi)]^2*h = c^2*h/(4*pi)
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.
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