Understanding Average Specific Heats in Fluid Mechanics Fundamentals

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mech-eng
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Textbook page excerpt: equations (2-9) du = cv dT and dh = cp dT for ideal gas, and (2-10) Δu = cv,ave ΔT and Δh = cp,ave ΔT using average specific heats.


I have been refreshing my fundamentals. Average specific heats are confusing for me. Why they are average? Are there different values for them so the averages are taken? Would you please explain this?

Source: Fluid Mechanics Fundamentals and Applications by Çengel/Boles.
Thank you.
 

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Line graph of specific heat C in J g^-1 K^-1 against temperature T in K from 0 to about 1100 K, showing C_v and C_p curves rising from near zero at low temperature and levelling off near 1.9 at high temperature.


Sure, many materials have specific heat values that change with temperature. The one above is for diamond.
 
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How can scientists measure these values? I think it should be very hard process.

Thank you.
 
mech-eng said:
How can scientists measure these values? I think it should be very hard process.

Thank you.
Read about Joule's experiments.
 
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