Question

In an adiabatic expansion of air the volume increases by 5%. What is the percentage change in pressure ? [(1.05) ^7/5 = 1.07]

• A. 7%
• B. 6%
• C. 4%
• D. 3%

Answer 1

Answer: (A)

7%

Answer 2

= $\mathrm { P } _ { 2 } \mathrm {~V} _ { 2 } ^ { \gamma }$ (g = 7/5), V₂ = 1.05 V₁

= P₂ (1.05 V)^g

P₂ = $\frac { \mathrm { P } _ { 1 } } { ( 1.05 ) ^ { \gamma } }$ so % change × 100

=×100= $\frac { 1 - ( 1.05 ) ^ { \gamma } } { ( 1.05 ) ^ { \gamma } }$ × 100 = 7%