A projectile is fired into a gas (ratio of specific heats \(k=1.625\) ) in which the pressure is \(450 \mathrm{kPa}\) absolute and the density is \(4.5 \mathrm{~kg} / \mathrm{m}^{3}\). It is observed experimentally that a Mach cone emanates from the projectile with \(25^{\circ}\) total angle. What is the speed of the projectile with respect to the gas?