If ΔQ and ΔW represent the heat supplied to the system and the work done on the system respectively, then the first law of thermodynamics can be written as(a) ΔQ = ΔU + ΔW(b) ΔQ = ΔU - ΔW(c) ΔQ = ΔW - ΔU(d) ΔQ = –ΔW - ΔU
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Greater than 0 .( First law of thermodynamics U=Q+W).
So answer is - A
See I can understand ,why you are confused. It's just because of sign convention.
Just remember -
If you give heat to any system it's energy will increase ( Pretty intuitive)
If you work on system then also it's energy will increase.
In both way you are giving energy to the system.
Ryt?
So when I write U= Q+ W , that means both Q and W are done on system not done by system.
So if work is done by system then it will be U=Q- W
If heat is removed from system then U= -Q+ W
So coming to original form.
U= Q+ W.
Or Delta U= Delta Q+ Delta W.
Now you can answer above these Question.
So answer is - A
See I can understand ,why you are confused. It's just because of sign convention.
Just remember -
If you give heat to any system it's energy will increase ( Pretty intuitive)
If you work on system then also it's energy will increase.
In both way you are giving energy to the system.
Ryt?
So when I write U= Q+ W , that means both Q and W are done on system not done by system.
So if work is done by system then it will be U=Q- W
If heat is removed from system then U= -Q+ W
So coming to original form.
U= Q+ W.
Or Delta U= Delta Q+ Delta W.
Now you can answer above these Question.
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