Show all work for full credit. Extra paper is available. Circle final answers, a
ID: 2263074 • Letter: S
Question
Show all work for full credit. Extra paper is available. Circle final answers, and include units.
(10 points) Circle all the following that are true about the polytropic process Pvn = constant.
(a) A polytropic process is always isothermal.
(b) A polytropic process is never isothermal.
(c) A polytropic process is sometimes isothermal.
(d) Only ideal gases perform polytropic processes.
(e) Only non-ideal gases perform polytropic processes.
(f) The polytropic exponent, n, is a material property (i.e. only one value of n for air)
(g) The polytropic exponent, n, varies with the rate of heat transfer, Q.
Note: I'd like to know which a-g, are correct.
Explanation / Answer
(c) A polytropic process is sometimes isothermal.
This is correct because if n=1 then "p V = N k T = constant"
(d) Only ideal gases perform polytropic processes.
The polytropic process equation is usually applicable for reversible or irreversible processes of ideal gases.
(g) The polytropic exponent, n, varies with the rate of heat transfer, Q.
"n", which is usually determined from experiment, depends upon the equation of state of the gas and the amount of heat transferred.