What is the first law od thermodynamics? How is this law applicable to the Earth's energy balance?

1 Answer
Marta O.
Mar 21, 2018

The first law of thermodynamics says that the change in internal energy of a system ΔU equals the net heat transfer into the system Q plus the work done on the system.

#ΔU=Q+W#

Explanation:

A body in space (Earth) is being radiated by a star, the Sun, and then if it remains at a constant temperature, it must radiate out as much energy as it receives.
![https://en.wikipedia.org/wiki/Earth%27s_energy_budget#/media/File:The-NASA-Earth%27s-Energy-Budget-Poster-Radiant-Energy-Systemhttp://-satellite-infrared-radiation-fluxes.jpg](https://useruploads.socratic.org/7FKJUn55Saw0fvLlsGmw_The-NASA-Earth%27s-Energy-Budget-Poster-Radiant-Energy-System-satellite-infrared-radiation-fluxes.jpg) #->#the balance of incoming and outgoing radiation on Earth

So, if the temperature #T# of the gas increases#-># the Earths atmosphere, the gas molecules speed up and the internal energy #U# of the gas increases (#ΔU# is positive). If heat exits the gas#->#the Earths atmosphere, #Q# will be a negative number.KhanAcademy_the firts law of thermodynamics

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