Hi Suppose there is a 1 m3 cylinder containing 1.3 kg air at 25 C. The cylinder is sitting in a vacuum place. The air inside the cylinder will exert a pressure of almost 1 atm. The cylinder also has a valve which can be opened to let the air out into surrounding vacuum. The average speed of air molecules at 1 atm and 25 C is almost 450 m/s, and the speed of sound in air is 350 m/s. When the valve is open, what would be the speed of escaping of air molecules? 340 m/s or 450 m/s? Thank you for the help.