### Joule's Law

Joule's Law states, "The change of internal energy of a perfect gas is directly proportional to the change of temperature." Mathematically,

where

m = Mass of the gas, and
c = A constant of proportionality, known as specific heat.

Note: From the Joule's law, we see that whenever a gas expands, without doing any external work and without taking in or giving out heat, its internal energy as well as temperature does not change.

### Are Engineers Favourite Among Girls?

What do girls think about men who are engineers and what type of engineers are most favourite among girls? A survey was conducted by a team of aboutmech with members chosen from different countries. Each team member carried out a neutral survey in his/ her country to evaluate what females think about most of the engineers from different engineering branches. An overview of different questions asked in survey is given below: Question: Which male engineers do you find more attractive as a husband? Almost 50% women voted for mechanical engineers to be the most attractive husbands among other engineers. So mechanical engineers are most favourite among girls as a husband. They find them more trustworthy, intelligent, and creative. A married women from California said, “If your husband is a mechanical engineer, he will help you in everyday tasks. Because mechanical engineers are good team players and they have creative ideas about everything.” Which male engineers do you find more