Question 435: Thermodynamics & KTG

Question

A litre of dry air at STP expands adiabatically to a volume of 3 litres. If $$\gamma $$ = 1.40, the work done by air is : (31.4 = 4.6555) [Take air to be an ideal gas]

Accepted Answer

$${P_1}V_1^\gamma  = {P_2}V_2^\gamma $$
$$ \Rightarrow $$ P
2
= P
1
$${\left[ {{{{V_1}} \over {{V_2}}}} ight]^\gamma }$$
= 10
5
$$ 	imes $$ $${\left[ {{1 \over 3}} ight]^{1.4}}$$
Work done = $${{{P_1}{V_1} - {P_2}{V_2}} \over {\gamma  - 1}}$$
= $${{{{10}^5} 	imes {{10}^{ - 3}} - {{{{10}^5}} \over {{3^{1.4}}}} 	imes 3 	imes {{10}^{ - 3}}} \over {1.4 - 1}}$$
= 88.7 J $$ \approx $$ 90.5 J

Answer

60.7 J

Answer

100.8 J

Answer

90.5 J

Answer

48 J

Thermodynamics & KTG

A litre of dry air at STP expands adiabatically to a volume of 3 litres. If $\gamma $ = 1.40, the work done by air is : (31.4 = 4.6555) [Take air to be an ideal gas]

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