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0.06 moles of a monatomic gas undergoes the cycle A ?B?C?A as shown on the P-V d

ID: 2161156 • Letter: 0

Question

0.06 moles of a monatomic gas undergoes the cycle A ?B?C?A as shown on the P-V diagram below.

(a) In the transition A?B the gas expands adiabatically from 1x10-3 to 2x10-3 m3 and the temperature drops from 600K to 400K. During this transition the internal energy reduces by 149 J. What is the work done on the gas? J

(b) During the transition B?C, the volume decreases from 2x10-3 m3 liters to 1x10-3 m3 liter at constant pressure (isobaric). What is the work done on the gas? J

(c) During the isobaric (constant pressure) transition B?C, what is the heat transferred to the gas? J

(d) During the constant volume (isovolumetric) transition C?A, the internal energy increases by 299 J. What is the heat transferred to the gas? J

(e) For the cycle A?B?C?A, what is the efficiency of the heat engine? %

(f) What is the efficiency for a Carnot cycle running between 200K and 600K. %

Explanation / Answer

a)

adiabatic >>>>> Q = 0

>>> W = -E = -149 J

b)

W = -P V = -1e5 * (1-2)e-3 = +100 J

c)

E = 3/2 n R T = (3/2)*0.06*8.314*(200-400) = -149.652

Q = E + W = -149.652 + 100 = -49.7 J

d)

E = Q + W = Q + 0

>>> Q = E = 299 J

e)

= W/Q = (149/299) = 0.498

f)

= 1 - Tc/Th = 1 - 200/600 = 0.667