Re: [Phys-L] playing for keeps

["John Clement" <clement@hal-pc.org>]

Yes, but that requires understanding proportional reasoning.

John M. Clement
Houston, TX 

> -----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 have 
> > memorized the formulas C = 2*pi*R and A = pi*R^2 but often 
> do not know 
> > which applies when to what, nor that there is any 
> connection to things 
> > they really do know. It would be awfully useful somewhere to start 
> > with the circumference being about 4*(2R) = 8R (the 
> circumference of 
> > the bounding square) and then see that this is only a bit 
> bigger 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 a 
> bit 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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