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)
Let h be the height of the liquid column.
The hydraulic pressure of the liquid is given by the equation,
P = ρ g h …… (1)
The blood pressure in a human body is directly proportional to the height of the column. Since the height of the column of blood flowing at the feet is more than that at the brain, so the blood pressure at the feet is more than the blood pressure at the brain.
(b)
From equation (1), it is observed that hydraulic pressure is directly proportional to the density of fluid. The density of air at 6 km height above sea level is about half of the density at sea level. Therefore, the pressure at the height of 6 km above the sea level is half of the pressure at sea level.
(c)
When external force is applied on any fluid, the particles of the fluid are transmitted in all possible directions. Therefore, the hydraulic pressure does not have any particular direction due to which it is a scalar quantity.
(a)
Let
The hydraulic pressure of the liquid is given by the equation,
The blood pressure in a human body is directly proportional to the height of the column. Since the height of the column of blood flowing at the feet is more than that at the brain, so the blood pressure at the feet is more than the blood pressure at the brain.
(b)
From equation (1), it is observed that hydraulic pressure is directly proportional to the density of fluid. The density of air at
(c)
When external force is applied on any fluid, the particles of the fluid are transmitted in all possible directions. Therefore, the hydraulic pressure does not have any particular direction due to which it is a scalar quantity.
