Mechanical Properties of Fluids – Solutions

1) Explain why

(a) The blood pressure in humans is greater at the feet than at the brain

(b) Atmospheric pressure at a height of about 6 km decreases to nearly half of its value at the sea level, though the height of the atmosphere is more than 100 km

(c) Hydrostatic pressure is a scalar quantity even though pressure is force divided by area.

Solution:

(a) The height of the blood column is quite large at feet than at the brain, consequently, the blood pressure in humans is greater at the feet than at the brain.

(b) The density of air does not decrease linearly with height. The density decreases rapidly up to a height of about 6 km and above 6 km, it decreases rather very slowly. So the atmospheric pressure at a height of about 6 km decreases to nearly half its value at the sea level.