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-----Original Message-----
From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of
Ludwik Kowalski
Sent: Saturday, June 29, 2013 5:30 PM
To: Phys-L@Phys-L.org; Bruce_Sherwood@ncsu.edu
Subject: Re: [Phys-L] playing for keeps
On Jun 29, 2013, at 5:17 PM, Bruce Sherwood wrote:
Good engineering and science students at good universities havedo not know
memorized the formulas C = 2*pi*R and A = pi*R^2 but often
which applies when to what, nor that there is anyconnection to things
they really do know. It would be awfully useful somewhere to startcircumference of
with the circumference being about 4*(2R) = 8R (the
the bounding square) and then see that this is only a bitbigger than
2*pi*R, and to start with the area being about (2R)^2 =4R^2 (the area
of the bounding square) and then see that this is only abit bigger than pi*R^2.
An example of confusion is the frequently seen A = 2pi*R^2.
2*Pi*r^1 length ( 1 dimensional object)
Pi*r^2 area ( 2 dimensional object)
(4/3)*Pi*r^3 volume (3 dimensional)
Ludwik
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