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Grade 12Thermal Physics

An empty pressure cooker of volume 10 litres contain air at atmospheric pressure 10^5 Pa and temperature of 300 K. It contains a whistle which has area if 0.1 cm^2 and weight of 100 gm. What should be the Temprature of air inside so that the whistle is just lifted up? please need the steps of doing it

Profile image of Shuvam Shukla
13 Years agoGrade 12
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2 Answers

Profile image of kshitij  aggarwal
13 Years ago

First let us find the pressure at which whistle will be lifted. 

        P = mg / A

          = 105 Pa.

so it will be lifted at 300K only.

 If say the pressure inside the cooker at 300K be some other value,  then use P/  T1 = P2  / T2

Profile image of nimo jar
8 Years ago
Pressure by whistle = Po + F / A = Po​ + mg/ A
= 105Pa + (0.1 * 10 N) / (0.1 * 104 m2)
= 2 * 105 Pa
Pressure inside cooker = 105Pa
for whistle to just lift, by gay lussacs law
Pwhistle / Tsurrounding = Pcooker / Tcooker
(2 * 105 Pa) / 300 K = 105 Pa / T
T = 600 K = 327oC