Question

A typical human blood pressure reading is "120/80". The measurement units are based on a mercury manometer. Calculate the numbers if measured on the moon, where the gravitational acceleration is 1.6 m/s^2, also with a mercury manometer. The density of mercury is 13.5 g/cm^3.

Please show full working with explanations.

Answer 1

We know that

density = mass/volume

mass = density x volume

P = F/A

F = mg

mass, density, volume and A remains same at moon.

P1 = rho V g/A

P2 = rho V g'/A

P2/P1 = rho V g'/A x A/rho V g

P2 = 1.6/9.8 P1

P2 = 0.163 P1

So the Pressure at moon will be:

P2 = 120 x 0.163/80 x 0.163 = 19.56/13.04 mm Hg

Hence, P2 = 19.56/13.04

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ratio of acc. due to gravities

g/g' = 9.81/9.8 = 6.13125

New pressure will be:

P' = 6.13125 x 120/ 6.13125 x 80 = 736/490 mm hg

Hence, p' = 736/490 mm Hg