Please explain better about creating volume. It takes less material to get say, a 1" cross section. A cylinder will touch at 4 points in a rectangular opening battery pack. A 1" square bottle or can holds more volume than a 1" dia. cylinder. 1 x 1 = 1 sq, inch pi r2 (0.05 x
0.05) = 0.785 sq. inch. A square battery could have more power packed in the space than a round (cylinder) shaped one.
So those 9V batteries and lantern batteries are no good? I guess I should toss them.
On Fri 22 Sep 2017 05:18:26p, Ed Pawlowski told us...
There are some round 9V batteries that are round, but they're not compatible with the rectangular ones.
First, when you are measuring the area of a cross-section, notice that you get inches^2, rather than inches. I use "in" below. If we have a string of length L forming a circle (of unknown radius r). Then L =
2*PI*r (circumference formula), so r = L/(2*PI), and consequently the area of the cross section is (from the area formula) A_1 = PI*r^2 = PI *(L/(2*PI))^2 = L^2/(4*PI) in^2.The area of a rectangle having perimeter L is maximized when the rectangle is a square (that's a separate problem I won't go into now). However, in this case, where we have a square cross section, we we get side length s = L/4, so A_2 = (L/4)^2 = L^2/16 in^2.
We conclude that A_1/A_2 is about L^2/(4*PI) /(L^2/16)= 16/(4*PI) = 4/PI is about 1.27.
So A_1 is about 1.27 times the area of A_2.
Note that the result, does not depend on the value of L. Let me know if you have any questions or if you find an error (they happen!) : )
Bill
AA batteries are round for the same reason that manhole cover are round.
Cindy Hamilton
WTF does your square have to do with volume?
So in conclusion: A 1" square bottle or can hold more volume than a 1" dia.
Rectangular packaging is more efficient use of space than cylindrical.
He's showing that you get maximum area with a given length bit of string if you arrange it in a circle rather than a square. This also means that if you battery is constant cross-section, as an AA is, the best shape for it to have to minimise the amount of case-material used to make it, is a cylinder.
That makes some sense. I don't know if batteries need a constant cross section but they may to have the best chemical reaction.
I think not...
A battery holder if built on same sizing principle wouldn't let battery into its opening rendering it pretty much useless...
So they can't get dropped down a hole? The folks makin' the batteries best do some thinkin'.
From the point of view of minimizing the use of materials for an enclosure, the *sphere* does best. And, I can't think of any reason why this wouldn't be a great design (ha!) ; )
Manhole covers are round so they can't fit through their own holes.
Yes.
Spherical batteries would waste a lot of space between them. You'd need larger flashlights.
What do you mean, "them". You would only need one appropriately-sized battery (using more than one would be a waste of materials!) : )
But isnt necessarily needed with torches etc.
Tho we have seen the big square batterys used for those too.
Why not say "torches"? they don't flash, most people turn them on, not on and off and on and off.
That sounds positively kinky.
On Fri, 22 Sep 2017 20:22:18 +0100, Tekkie=AE wrote= :
re square in crosssection, they wouldn't roll off the desk.
At least I don't roll away. Place an AA on your desk, attempt to touch = the ends with a multimeter. Chase battery around the desk, pick it up o= ff the floor, then try again.
-- =
"Beam me aboard, Scotty!" [-] "Will a 2 X 4 do, Captain?"
I thank you for your useful input to the discussion. Grow up.
Round is hard enough!
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