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Power cost of idle electric water heater
wrote:
Jonathan Ball wrote:
...Take a 1-foot cube, 1 x 1 x 1. The volume is 1 cubic
foot, and the surface area is 6 square feet. An n x n
x n cube of 2 cubic feet will have n = (approx) 1.26.
The surface area is 6 x 1.25^2 = 9.52 sqare feet. The
volume has doubled, but the surface area has gone up by
LESS than twice.
A lovely explanation, but larger tanks lose more heat.
Not relative to volume.
Who cares about volume?
Anyone who is concerned with temperature change.
Why did you snip out my experiment, bozo, without
noting your snip? Here, try it:
On a cool night, fill the largest kitchen pot you have
with water, almost to the brim, and bring it to a boil.
When it reaches boiling, take the pot of water and an
empty 1-cup measuring cup outside. Set the pot down,
and dip the measuring cup into the hot water and fill
it. Set it down next to the pot. Place the pot's
cover on the pot, and some type of covering on the
measuring cup; maybe a saucer. Go back into the house
and pour yourself some more of your cheap vodka.
45 minutes later, go back outside, and remove the
covers from the pot and the measuring cup. Stick your
fingers in the measuring cup, and decide if the water
feels cold, cool, tepid, warm or hot. Now do the same
with the large pot of water. You will find the water
in the large pot is substantially warmer than the water
in the cup.
Here's another experiment for you, bozo. Get a small
individual-serving plastic yogurt container, and a
larger 32 oz. plastic container. Fill them both with
tap water, then put them in your freezer. Check on
them every 45 minutes. Tell us which one freezes
solidly first.
The RATE of heat loss is based on the ratio of the
surface area to the volume, and because the larger
vessel has a SMALLER ratio of surface area to volume,
it will lose heat at a slower rate.
I'm afraid you are wrong, my good man. The rate of heat loss
(vs temperature change) is directly proportional to the amount
of surface. This is known as "Newton's law of cooling."
You're wrong, bozo. Newton's Law of Cooling states
that the rate of temperature change in an object is
proportional to the DIFFERENCE in temperature between
the object and the ambient air temperature. It doesn't
include a variable for surface.
Note also, bozo, that the law applies to the
temperature *of the surface* of the object.
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