Example 3 A 10 m3 rigid tank has two sections separated by a membrane. Each section contains nitrogen gas.The nitrogen gas in section A has initial density of 1.6 kg/m3 and the nitrogen gas in section B has a mass of 6 kg,At a certain time,the membrane is punctured.The final density of the nitrogen gas in the tank is found to be 1.8 kg/m3. Determine the initial density(kg/m3)of nitrogen gas that existed in section B. Given VA+V8=10 m PA1 =1.6 kg/m3 A B MB=6kg P2=1.8kg/m3 Solution MA+Mg=P2×(Wa+'g)=1.8kgm3×10m3=18kg MA=18-MB=18-6=12kg MA= 12kg PA 1.6 kg/m3 =7.5m3 V='amk-'a=10-7.5=2.5m3 上游充通大学 M=6kg、=24kg/m 2.5m February 28,2019 24 SHANGHAI JIAO TONG UNIVERSITYFebruary 28, 2019 24 Example 3 3 3 A B A1 3 B 2 10 m 1.6 kg/m 6 kg 1.8 kg/m V V M        Given Solution 3 3 3 3 3 3 A B 2 A B A B A A A1 B tank A B 1 B 3 1.8 kg/m 10 m kg 18 18 6 kg 12 kg ( 18 12 m 1.6 kg/m 10 7.5 m 6kg kg/m 2. ) 7.5 2.5 2.4 5 m B M M V V M M M V V V V M V                          