expansion
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Re: expansion
Generally, an expansion done by the system is negative work (i.e. the system is investing energy into pushing a piston) and a compression of the system is positive work (i.e. the system is gaining energy as a result of the compression by some factor).
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Re: expansion
Work being done on the system typically compresses the volume of the system and work is positive. On the other hand, work being done by the system, the volume of the system typically increases and the work is negative.
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Re: expansion
When a system does work on the surroundings, as a result the system's capacity to do work would decrease. Imagine the piston example where the system is pushing against the surrounding more to expand. This causes the work to be negative and energy to be lost.
When the surroundings does work on the system, as a result the system's capacity to do work would increase. In the piston example, this would be shown by the system basically letting the surrounding compress it so that the system's ability to do work will increase and energy is gained since the system is not really using energy to push back against the surrounding during compression. Hope this helps!
When the surroundings does work on the system, as a result the system's capacity to do work would increase. In the piston example, this would be shown by the system basically letting the surrounding compress it so that the system's ability to do work will increase and energy is gained since the system is not really using energy to push back against the surrounding during compression. Hope this helps!
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Re: expansion
Hello! Expansion is work being done by the system, so the system’s work is negative. On the other hand, compression is work being done on the system, so the system’s work is positive.
Hope this helps!
Hope this helps!
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Re: expansion
We can tell if expansion is working against or with the system by the value, specifically sign, of the system's work. If work is being done ON the system, the work would be positive because the system's internal energy is increasing(deltaU= q+w). If work is being done BY the system, the system is using its internal energy in the form of work, so it would be work would be negative.
Re: expansion
Work being done on the system compresses the volume of the system and work would be positive while work being done by the system means the volume of the system would increase and the work would be negative.
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Re: expansion
When a gas is compressed, work is being done on the system however, when a gas expands, the system is doing work. To compress a gas, for eg a bicycle pump, energy from us is required and therefore we are the ones doing the work on the system. In this case, the internal energy of the system increases. When a gas expands, it is pushing against an external pressure to do so and therefore it is the one doing the work. In this case, the internal energy of the system decreases.
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Re: expansion
Expansion is working against the system when the system shrinks, or when work is done on the system. This is usually when work is a positive value. Expansion is working with the system when the system expands, or work is done by the system. This is usually when work has a negative value.
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