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