Question

When Internal Energy is negative U1>U2? Can anyone give example when internal energy is negative in Real-life​

Answer 1

Answer:

So a negative change means the final energy is lower than the initial energy. This results in energy "out of the system." In words this might be stated as energy flow "out of the system" or "released by the system." A positive change indicates the system has "absorbed energy" or "increased in energy" or "taken in energy."

Explanation:

ΔU<0 Energy goes from system to surroundings

ΔU>0 Energy goes from surroundings to system

The same is true for the sign convention of heat.

q<0 Heat is flowing out of the system into the surroundings. Heat is released.

q>0 Heat is flowing from the surrounding into the system. Heat is absorbed.

w<0 is work out of the system. We say the system does work on the surroundings.

w>0 is work into the system. The surroundings do work on the system.