The 1st Law of Thermodynamics in Your Kitchen
A simple way to understand this equation Q=ΔU+W
The first law of thermodynamics can be expressed mathematically as:
ΔU=Q-W or Q=ΔU+W
Where:
ΔU represents the change in Internal Energy of a system,
Q represents the Heat added to the system, and
W represents the Work done by the system.
[Remember that Internal Energy is a function of Temperature only]
Let’s apply this equation to an everyday example — Boiling Water on a Stove.
When you put a pot of water on a stove and turn on the heat, you’re adding Heat Q to the system.
- The water absorbs this heat, causing its Internal energy ΔU to increase as its temperature rises.
- If the water starts to boil and produce steam, Work W is also done by the system (expansion of the water into steam).
- So, the change in Internal energy ΔU of the water is equal to the heat added minus the work done (ΔU=Q-W)
Or in other words — the Heat Q added to the system changes the Internal Energy ΔU of the system and the system (water) does Work W
The first law of thermodynamics is evident here , showing how the change in internal energy of a system is related to the heat added to the system and the work done by the system, as described by the equation.
…Once or twice I have been provoked and have asked the company how many of them could describe the Second Law of Thermodynamics. The response was cold: it was also negative. Yet I was asking something which is the scientific equivalent of: Have you read a work of Shakespeare’s?…
C. P. Snow : The Two Cultures and the Scientific Revolution
