The internal energy of the gas in a gasoline engine’s cylinder decreases by 278.9 J.
If 53.0 J of work is done by the gas, how much energy is transferred as heat?
Answer in units of J
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2014-05-04 2:52 am
回答 (1)
2014-05-04 3:31 am
According to the first law of thermodynamics, in a close system:
Change in internal energy = heat transfer TO gas + work done TO gas
-278.9 = heat -53
heat = 225.9J.
225.9J of heat is transferred from the system to the surrounding
Be careful with the word 'to' or 'by'. Work done to the system by the surrounding increases the internal enegy of the system whist work done by the energy to the surrounding decreases the internal energy of the system.
Similarly, If the system is giving out heat (heat transfer by the system, to the surrounding), the systems internal energy decrease. vice versa.
Change in internal energy = heat transfer TO gas + work done TO gas
-278.9 = heat -53
heat = 225.9J.
225.9J of heat is transferred from the system to the surrounding
Be careful with the word 'to' or 'by'. Work done to the system by the surrounding increases the internal enegy of the system whist work done by the energy to the surrounding decreases the internal energy of the system.
Similarly, If the system is giving out heat (heat transfer by the system, to the surrounding), the systems internal energy decrease. vice versa.
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