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Posted by Eeyore on April 17, 2009, 11:39 am
 


Curbie wrote:


That's because those using Fahrenheit and pounds amount to under 5% of the
world population.

Graham


Posted by Scott on April 17, 2009, 2:24 pm
 
On Fri, 17 Apr 2009 12:39:47 +0100, in alt.energy.homepower, Eeyore



Posted by Eeyore on April 17, 2009, 6:38 pm
 

Scott wrote:



Posted by Eeyore on April 17, 2009, 11:38 am
 

harry wrote:


I started learning physics briefly using British units and then we moved to
metric, firstly cgs for a while and then rapidly to MKS which is pretty
similar to SI. My results suddenly shot up using metric.

Graham



Posted by daestrom on April 17, 2009, 12:59 am
 

Actually, it *does* use conversion factors, it's just that they all happen
to be 1-something (1J = 1 N-m, or 1W = 1 J/s)

If you don't keep track of the units being used, it's just as easy to screw
up something in the SI system as any other.  Can't tell how many times I've
caught students trying to say 1m + 1 N = 2J.  Ever try to add units of
length with units of force?  Keeping track of the units and using even SI
conversions is essential to doing the right calculations.

Where did you Europeans ever get the idea to measure force using kilograms
anyway?  While the proper unit for pressure is the Pascal (or kPa or MPa),
why do you have pressure gauges that measure 'kg / cm^2'?  What's up with
that?

Not that I'm a big fan of the US imperial system, but there are a few tricks
that work well.  One lbm always exerts one lbf due to gravity.  Heating up
one lbm of water one degree F takes just one BTU.  Maybe a few others.

daestrom


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