One way to administer an inoculation is with a "gun" that shoots the vaccine through a narrow opening. No needle in necessary, for the vaccine emerges with sufficient speed to pass directly into the tissue beneath the skin. The speed is high, because the vaccine (? = 1170 kg/m^3) is held in a reservoir where a high pressure pushes it out. The pressure on the surface of the vaccine in one gun is 4200000 Pa above the atmospheric pressure outside the narrow opening. The dosage is small enough that the vaccine's surface in the reservoir is nearly stationary during an inoculation. The vertical height between the vaccine's surface in the reservoir and the opening can be ignored. Find the speed at which the vaccine emerges.