a cannon fires a shell that causes a projectile to move down the barrel at a velocity of 600 m/s. what is the speed of the normal shock proceeding down the barrel in front of the projectile and the pressure and temperature experienced by the front face of the projectile? the undisturbed air in the barrel is at 101 kpa and 300k. how fast would the projectile have to be moving down the barrel if the velocity of the shock ahead of the projectile was 3 times the velocity of the projectile?