Question

The atmospheric pressure is 75 cm of mercury. Express it in Nm^-2.

Answer 1

The pressure is given by P = h Xp Xg.
Where h is the height of the liquid column, p is the density of the liquid, g is the acceleration due to gravity.
Density of mercury is = 1.36 X10⁴ kg/m³.
h = height of mercury column which is given = 75 cm = 0.75 m.
So pressure = 0.75 X 1.36 X10⁴X9.8 = 9.996X104Nm^-2.