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?

We can use P1/T1=P2/T2                      (where P1=Patm      T1=300k)

NOw to lift the weight a force needs to be applied on the weight which is greater than or equal to its weight

hence,F=mg     (where F is the minimum force required to lift the weight)

This force can be provided by the pressure (P2) inside the cooker

hence,

F=(P2)A  (where A is the area of cross section)

hence,

(P2)A=mg

find P2 from this and substitute in the first equation to get the answer 

according to ur method P2 is 300k same as P1.. but the answer is 327K