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Generating Power With a Bicycle
Name: Jerry
Status: Other
Grade: Other
Location: NY
Country: United States
Date: November 2007
Question:
Can I make an ice cube with a bike?
(guaranteed to be an original question!) We are a
group of long distance sailors who sometimes find
ourselves in remote parts of the world. It is nice
to have a fridge on the boat on these trips, but
boat fridges are take up valuable space, break a
lot, and require you to run the engine every day
just to keep them cold. I do without a fridge, but
really miss having ice cubes in my drink at the end
of a hard day's sailing. I joked to my friends that
I should hook up my bike (on board the boat) to a
condenser. I could then peddle to pressurize the
Freon, which would be expanded around a container
just big enough to freeze one ice cube. My idea was
met with skepticism, since most believe you would
have to bike a long time. So our question (finally)
is: how long would a reasonably fit person have to
bike to generate enough power to make an ice cube
from room temperature water? I did some calculations
and came up with one minute. But this just sounds
wrong.
Replies:
Hi Jerry,
Well, yes, that definitely was an original question! The
answer is there is no problem in one person providing enough
"power" to run the compressor. A normal refrigerator
compressor only uses about 1/3 horsepower, and a reasonably
fit human should have no problem generating that much
power....
....for a short time! And therein lies the problem. It
typically takes an hour or two for a normal refrigerator to
freeze ice cubes. So the question is not whether you could
supply enough power, but rather can you supply enough energy.
That is, the product of power and time! My suspicion is that
you are going to get very tired before the water freezes!
Regards,
Bob Wilson.
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