w of Thermodynamics Lab 12 Heat Engines and the First Law of Therm L 12-4 Vb Va

Question

w of Thermodynamics Lab 12 Heat Engines and the First Law of Therm L 12-4 Vb Va Hopefully, you answered W=pAV and that this is just the area under the p vs. turns out mathematically that you can always calculate the work done by finding the a vs. V curve. It rea unde the curve, even if the pressure does not remain constant during the process. Also, the wo calculated in this way is positive if the gas expands in the process. If the gas is compresse during the process, then work is done on the gas by the surroundings, and the work done byt system is negative. Examples are shown below.

Explanation / Answer

from the graph give process is isobaric expansion

that is at constant pressure volume expands from intial volume to final volume

so simply work done from the graph is area under the curve

from the graph area is similar to the rectanglee

area od recangle = length *bredth

here area under the curve is work = pressure*change in volume

W = p*(Vb-Va)

or from the first law of thermodynamics

dQ = dU+dW

dW = dQ-dU

here Q = heat energy

U = intwrnal energy

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