Question

What will be the length of a mercury column in a barometer tube, when the atmospheric pressure is 75cm of mercury and the tube is inclined at an angle of 60° with the horizontal direction?

(a) 8.66cm

(b) 86.6cm

(c) 866cm

(d) 0.866cm

This question was addressed to me in examination.

This question is from Thrust of a Liquid in section Mechanical Properties of Solids of Engineering Physics I

Answer 1

Correct choice is (b) 86.6cm

The explanation: If l is the length of a mercury column in the barometer tube, then

h/l=sin60

75/l=√3/2

l=(75×2)/√3=86.6cm.