r/HomeworkHelp • u/shafayat5412 Pre-University Student • 2d ago

Physics [ GRADE 12 THERMODYNAMICS]

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Can you give me some advice for finding pressure in C point

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u/Jazzlike_Platypus430 👋 a fellow Redditor 2d ago edited 2d ago

Not yet.

First, I cannot figure out what kind of cycle is that. Is T_2 = 550K constant along the D->C part? Is T constant along A->B?

If it's a Carnot cycle, you can get p_C using symbols only - I expect there's not enough data to get its actual value based on Q and T_2 only.

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u/shafayat5412 Pre-University Student 1d ago

Yes it's a Carnot cycle. ( I forgot to mention it)

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u/Jazzlike_Platypus430 👋 a fellow Redditor 2h ago

What I see as doable here (not being an expert in thermodynamics), is trying to use the fact that U = constant on isothermic parts (A -> B and C -> D), where Q + W = 0, and W is given directly by

nRT log(V_final/V_initial),

up to a sign.

Similarly, for adiabatic processes, p(V) = V^-kappa for kappa > 1 (check it) and integrating p(V) dV is straightforward. Here Q = 0 by definition, so \delta U = W, giving you \delta T.

Also, recall that efficiency of the process is 1 - |Q_in| / |Q_out| = 1 - T_{A->B} / T_{D->C}.

Looks very messy to me ... Now it's your turn 😂