Explain why (a) the blood pressure is humans is greater at the feet than at the brain.
(b) Atmospheric pressure at a height of about 6 km decreases to nearly half its value at the sea level through the 'height' of the atmospheric is more than 100 km.
(c) Hydrostatic pressure is a scalar quantity even though pressure is force divided by area , and force is a vector.

Explanation

(a) The height of the blood column is more for feet than for the brain in a human body, As the pressure increases with depth . Therefore, the blood exerts more pressure at the feet at the brain.
(b) As the density of air is naximum at the earth.s surface and decreases rapidly with the height initially, and at a height of 6 km it becomes half. As the pressure is directly proportional to the density. Therefore, atmospheric pressure at a height of about 6 km decreases nearly to half its value at the sea level.
(c) Due to the force applied on a liquid, the pressure is transmitted equally in all the directions and there is no particular direction for the pressure. Hence, the hydrostatic pressure can be taken as a scalar quantity.