Physics

1 Law of Thermodynamics


We call the first law of thermodynamics the principle of energy conservation applied to thermodynamics, which makes it possible to predict the behavior of a gas system when undergoing a thermodynamic transformation.

Analyzing the principle of energy conservation in the context of thermodynamics:

A system cannot create or consume energy, but only store it or transfer it to its environment, as work, or both at the same time, so when it receives a quantity Q of heat, it may do some work and increase the internal energy of the system ΔU, that is, expressing mathematically:

Being all units measured in Joule (J).

Knowing this law, we can observe its behavior for each of the presented quantities:

Heat Job Internal Energy Q //ΔU
Receive Performs Increases >0
Give in Receive Decreases <0
don't trade does not perform or receive doesn't vary =0

Example:

(1) When receiving a quantity of heat Q = 50J, a gas performs a work equal to 12J, knowing that the internal energy of the system before receiving heat was U = 100J, what will this energy be upon receipt?