Quote:
Originally Posted by katy
I understand co-efficient of thermal expansion, but what I'm trying to get my head around is what 10-6 in/in/ means.
10 minus 6 equals 4, that's pretty simple, but then what does in/in/ mean?
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"10^-6" is scientific notation for 0.000001. "in/in" is a way of saying "this is a unitless coefficient." Per degree is as stated.
That way, you can multiply your original length of material by a tiny coefficient specific to that material and arrive at what happens during a temperature change.
As midgetracer says;
The material expands in length .000001 inches per inch/ degree F.
Where CTE = .000001, x = 120 in, deltaT = 100 deg:
deltaX = .000001 * 120 in * 100 deg = .12 in.
To double check our logic, the units are:
(in/in /deg) * (in) * (deg) = (in*in/in)*(deg/deg) = in.
Makes sense.
But like I said several posts ago, someone should just measure the end of the tail pipe against a known datum at hot vs cold and see how little it actually moves.