Question

The diagram shows a
simple mercury barometer.
The mercury level is at a
height h when the atmospheric
pressure is 100000 Pa.
What is the pressure at P?
(A) 40000 Pa
(B) 60000 Pa
(C) 100000 Pa
(D) 140000 Pa​

Answer 1

The pressure at P will be-

(A) 40000 Pa

Fluid pressure is defined as "a measurement of the force per unit area on a object in the fluid or on the surface of a closed container."

Fluid pressure formula is given by -

P = rho*g*h

Since we are dealing with water in question, rho and g will remain constant.

Given values in question are -

P1 = 100000 Pa.

P2 = ?

H1 = h

H2 = 0.4h

So according to the formula,

P1/P2= H1/H2

100000/P2 = h/0.4h

P2 = 0.4*100000

P2 = 40,000 Pa.

Hence, pressure at point P will be 40,000 Pa.