10.1 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.
(a)The pressure of a liquid is given by the relation:
P = hρg
The height of the blood column is more for the feet as compared to that for the brain. So, the blood pressure in humans is greater at the feet than at the brain.
(b) The air pressure at a height h is given by P = P0e–αh where P0 represents the pressure of air at sea-level and α is a constant. The variation of air-density with height is not linear. So, we can conclude that pressure does not reduce linearly with height
c) When force is applied to a liquid, the pressure in the liquid is transmitted in all directions. Hence, hydrostatic pressure does not have a fixed direction and it is a scalar physical quantity.
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