One way to administer an inoculation is with a "gun" that shoots the vaccine through a narrow opening. No needle is necessary, for the vaccine emerges with sufficient speed to pass directly into the tissue beneath the skin. The speed is high, because the vaccine (ρ = 1100 kg/m3) is held in a reservoir where a high pressure pushes it out. The pressure on the surface of the vaccine in one gun is 4.1 × 106 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. |
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