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Question about temperature and Specific Weight 
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#1
Dec3013, 12:20 AM

P: 5

Hello,
I know there are many different representations of temperature, there's 4, 1) Fahrenheit 2) Kelvin 3) Celsius then there's 4) T = 460 + F In my fluid dynamics review book To calculate specific weight γ= P(pressure) / (R * T) = lb/ft^3, it explained that T should be absolute temp so I used 2) kelvin, but the book used 4) T = 460+F Can somebody explain what 460 + F stands for?? Thanks, Peter 


#2
Dec3013, 03:24 AM

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P: 23,393

Absolute in this context means any scale for which zero is at absolute zero. 460+F is also known as a Rankine scale.



#3
Dec3013, 01:24 PM

P: 5

So Rankine scale goes with british units lb/ft^3 and kelvin scale goes with international units like kg/m^3?



#4
Dec3013, 02:05 PM

Admin
P: 23,393

Question about temperature and Specific Weight
Not necessarily. Units used will change the R value  it can be calculated to use any combination of mass, length and temperature units (http://en.wikipedia.org/wiki/Ideal_gas_constant  see the table on the right). The only important thing is that the temperature scale is absolute (as explained in my previous post).



#5
Dec3013, 08:14 PM

P: 55

1 °Ra is equivalent to a change of 1 °F. Whereas 1 Kelvin is equal a change of 1 °C. 


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