Explain why
a) The blood prssure 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, thought the height of the atmosphere is more than `100` km.
c) Hydrostatic pressure is a scalar quantitys even though pressure is force divided by area.

Explanation

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" =hrhog`)
b) We know that the density of air is maximum near the surface of earth and decreases rapidly with height and at a height of about `6` km, it decreases to near by half its value at the sea level. Beyond `6` km height the density of air decreases very slowly with height. Due to this reason, the atmospheric pressure at a height of about `6` km decreases to nearby half of its value at sea level.
C) Since due to applied force on liquid, the pressure is transmitted equally in all directions inside the liquid. That is why there is no fixed direction for the pressure due to liquid. Hence hydrostatic pressure is a scalar quantity.