Re: Unit of measurement

Tim McDaniel <tmcd@xxxxxxxxx> wrote:
"one Sverdrup (Sv) is defined as a flow of one million cubic metres
of water per second".

There are lots of weird and wonderful units. In fact, there are two
others abbreviated Sv: The sievert, a unit of radiation exposure,
and the svedberg, a unit used with ultracentrifuges.

I can't think of any possible use I might have for this unit in real
life (unless I want to say "I had to use the urinal so bad, I think
I >hit 5 Sv"), ...

For any unit, including this one, it can be fun and informative to
get a piece of lined paper, let every line represent a factor of ten,
and set down where various very different things are. In this case,
anything that's a flow of a liquid. There would be a point for your
urine stream, and another for the Gulf Stream. What are the smallest
and largest flows you can think of?

Better yet, use graph paper, and two units at right angles. Volume
and mass are good choices. You should be able to fit everything from
an atom to the the known universe on the sheet. Objects of constant
density fall on a 45 degree line. How do the densities of an atom, a
person, a star, and the known universe compare? Where is the mass of
a person compared to the mass of an atom and the universe? Near the
center, or much closer to one side than the other? How about the
volume of a person?

Time, velocity, and power output are other good choices. It was by
graphing power output against mass that I realized that people produce
about 10,000 times more heat than the sun, per unit mass per unit time.

... my urine would hit 332 times the speed of light.

Yes, it's fun to divide absurd numbers by each other.

I can remember when the usual repository for digital data was punched
cards. Suppose someone wanted to play DVD-quality video from cards.
How big a deck would it take to hold a movie, and how quickly would
the cards have to move through the card reader?

How long would it take to download a movie using morse code?

How many hours of DVD-quality video could be stored in Avogadro's
number of bits? (Or is "hours" the best unit?)

How long would it take the Earth to spiral into the sun due to its
gravitational wave radiation? How about for a frictionless one-meter
one-kilogram one-second pendulum to lose energy by that mechanism?

How long would it take to travel to another solar system at walking
speed? (This could be done by constructing a very long rotating
cylinder between the solar systems, suitable for walking in.) How
about visiting *all* the solar systems in our galaxy? What about
doing so at the speed at which stalactites typically grow?

How big could you make a clock face before the end of the second hand
had to exceed the speed of light? The minute hand? The hour hand?

How big a telescope would it take to be able to read newspaper
headlines in another solar system from here?

How long would it take the fastest supercomputer to factor RSA-2048
by trial division? How long would it take a person with pencil and
paper, and how many pencils and how much paper would be needed?

If you never trimmed your fingernails, how long until you could
scratch the moon?
--
Keith F. Lynch - http://keithlynch.net/
Please see http://keithlynch.net/email.html before emailing me.
.

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