Question

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..​

Answer 1

Answer:

(a) The height of the blood column is more for the feet as compared to that for the brain.

(a) The height of the blood column is more for the feet as compared to that for the brain.Consequently, the blood pressure in humans is greater at the feet than at the brain.

(a) The height of the blood column is more for the feet as compared to that for the brain.Consequently, the blood pressure in humans is greater at the feet than at the brain.(b) The variation of air-density with height is not linear. So, pressure also does not reduce linearly with height. 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.

Answer 2

(a) The height of the blood column in the human body is more at feet than at the brain. That is why, the blood exerts more pressure at the feet than at the brain.

(Pressure =ρgh )

where h= height,  ρ =  density of liquid and g= accleration due to gravity)

(b) Density of air decreases very rapidly with increase in height and reduces to nearly half its value at the sea level at a height of about 6 km. After 6 km, the density of air decreases but rather very slowly.

(c) When force is applied on a liquid, then according to Pascal's Law, 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.