Work
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Work
How can we determine whether the work is performed by or on the system? What makes work positive or negative in terms of the system?
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Re: Work
Work is positive (done on the system) if it adds energy to the system. For example, if you increase the pressure of a gas using a piston, you are doing work on the gas because you are adding energy to it. If you heat a gas, you are adding energy to it, therefore you are doing work on it.
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Re: Work
If work is done on the system it is positive. If work is done by the system it is negative. This is kind of like temperature changes in a system being endothermic and exothermic. If heat is being given into a system it’s positive and if heat is leaving the system it’s negative.
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Re: Work
I think of work like exothermic and endothermic. Doing work on a system is positive because you are adding energy. Work by a system is negative because energy is released.
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Re: Work
If work is positive, then it is adds energy into the system. If it is negative, energy is released!
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