Question

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1. An ideal gas expands at a constant pressure of 6.00 105 Pa from a volume of 1.00 m3 to a volume of 4.00 m3 and then is compressed to one-third that pressure and a volume of 2.50 m3 as shown in the figure below before returning to its initial state. How much work is done in taking a gas through one cycle of the process shown in the figure?

2. The work done by an engine equals one-fourth the energy it absorbs from a reservoir.

(a) What is its thermal efficiency?



(b) What fraction of the energy absorbed is expelled to the cold reservoir?

Answer 1

Given:

An ideal gas expands at constant pressure:

P = 105 pascals
V1 = 1 m3
V2 = 4 m3

then, the gas is compressed to 1/3 of the pressure and volume 2.50 m3.

Work at constant pressure:

W = PΔV

W = 105 pascals * (4 m3 - 1 m3)
W = 315 Joules

Work at constant volume is zero.