Question

The unit of surface tension is same as that of _________

(a) surface energy per unit volume

(b) force per unit area

(c) surface energy per unit area

(d) surface energy per unit length

This question was addressed to me during a job interview.

This is a very interesting question from Fluids Mechanical Properties topic in section Mechanical Properties of Fluids of Physics – Class 11

Answer 1

Correct answer is (c) surface energy per unit area

Explanation: Surface tension is defined as force per unit length or surface energy per unit area.                              The unit is therefore N/m.                                                                                                                 Another unit people use is J/m^2 (where J refers to joule, the unit of energy).                                                               But obviously it is equal to Nm/m^2  = N/m.