A 1 m3 rocket-propellant chamber is tilled with combustion gases at 3000 K and 7 MPa at the instant combustion ceases. The throat area of the nozzle is 0.1 m2. Estimate the time it takes for the chamber pressure to drop to 0.7 MPa. Assume that at the instant combustion ceases, the chamber propellant supply stops completely, and also that gamma = 1.2 and M = 20.