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### Delta U

Posted: Tue Feb 11, 2020 8:29 pm
What exactly is $\Delta U$? I know it means internal energy but I'm not sure what that means.

### Re: Delta U

Posted: Tue Feb 11, 2020 8:31 pm
It refers to the energy contained within a system

### Re: Delta U

Posted: Tue Feb 11, 2020 8:32 pm
So basically, U = q + w refers to the fact that it is the total energy that the system is involved with, i.e the energy from the heat generated or loss plus the energy of the work done on or against the system

### Re: Delta U

Posted: Tue Feb 11, 2020 9:49 pm
this is the internal energy of the system. so w would be the work either done by or on the system and q would be the heat either absorbed or given off by the system. the changes are looked at in the perspective of the system

### Re: Delta U

Posted: Tue Feb 11, 2020 10:24 pm
When solving for internal energy, it is helpful to keep track of the terms given in relation to the system and not the surroundings.

### Re: Delta U

Posted: Tue Feb 11, 2020 11:04 pm
Delta U is basically the internal energy of the system. When a system is isolated the delta U cannot change. Delta U changes by an input of energy via heat transfer or work due to compression/expansion.

### Re: Delta U

Posted: Sat Feb 15, 2020 6:03 pm
It's important to remember than delta U is the change in internal energy rather than just the internal energy of a system. It's a state function that looks at how the internal energy of a system changes over the course of a process (if a system releases or absorbs energy).

### Re: Delta U

Posted: Sat Feb 15, 2020 7:31 pm
Changes in internal energy are a function of initial and final states. When delta U is zero, a gas still can expand because it is a spontaneous process with an entropy increase.

### Re: Delta U

Posted: Sun Feb 16, 2020 8:07 pm
Delta U is the change in internal energy. Internal energy is the energy contained within a system.