The basic barometer can be used to measure the height of a building. If the barometric readings at the top and at the bottom of a building are 730 and 755 mmHg, respectively, determine the height of the building. Assume an average air density of 1.18 kg/m3.
The barometer is a scientific device which is used to find out the pressure at a point. The barometer reading at the top of the building is 730 mmHg and at the bottom is 755 mmHg.
The atmospheric pressure at the top
The density of mercury ρ =13600 kg/m3
Ptop =(13600 kg/m3)(9.8m/s2)(0.730m) 
The atmospheric pressure at the bottom
Ptop =(13600 kg/m3)(9.8m/s2)(0.755m)