B------C A----------D PV diagram, A goes to B, B goes to C, C goes to D, D goes

Question

B------C

A----------D

PV diagram, A goes to B, B goes to C, C goes to D, D goes to A

The PV diagram of a heat engine working with an ideal gas is given as shown. The gas starting at state A with PowerA=1.0E+5 Pa and VolumeA=6.00L is heated to stae B with PowerB=5.00E+5 Pa and VolumeB =6.00L. At state C, PowerC=PowerB and Volume C =10.0L, and at state D, Power D=1.00E+5 Pa and Volume D =12.0L. The system is returned to its original state A. Obtain the work done by the engine, the heat the engine receives from the hot source, and the heat exhausted by the engine if the engine efficency is e=38%.

Given:

a. Work=1200J

b.W=2000J

c.W=1900J

d. NA

Work=

Heat recieved=

Heat exhausted=

Chegg is my last option lol please help me.

Explanation / Answer

I hope you understood how i got the 2000 J value.

now, since the efficiency is given, the question is very simple.

efficiency is work done divided by energy input

in this case work ddone is 2000j, and efficiency is given as 38%

hence, 0.38 = 2000/ heat input

this gives us heat input as 5263 J

now, out of 5263 joules, 2000 is used to do work.and remaining ( 5263-2000 = 3263 J ) is discarded as exhaust heat.

please ignore the graph method I used to calculate heat input and exhaust.

My method is true for ideal scenario, where efficiency is maximum ( maximum possible )

but when efficiency is given, it is better to use the later approach as it is not ideal but practical engine

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