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Re: [Phys-l] Fun/cool unit conversion example?

At 2:16 PM -0700 1/18/10, Jeff Loats wrote:
On the first day of class I do a brief example to illustrate unit conversion
(snore) and I usually spice it up by making it very silly (such as density
measured in gigaslugs per parsec cubed).

I thought I would ask here to see if anyone had a neat unit conversion
example that left you with a sense of "huh, I didn't know that" or "that was
cool!" or something similar.

I tell them Benjamin Franklin was famous for hiding oil in the joint of his
bamboo cane and then "calming the waters" of a troubled pond by releasing
the oil on it. Turns out that one teaspoon of oil spreads out to cover
about 0.5 acre of pond. We then find the thickness of the monolayer of oil
by dividing one teaspoon by 0.5 acre. This gives practice with lots of
unit conversions, including some that have squares or cubes in them.
Getting the answer is a great time to introduce the SI prefix nano.

Another one I do later in the course is ask them if it would be cheaper to
buy energy as peanut butter calories at the store or as electricity from
the "power" company.