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Posted: Fri Jan 19, 2018 6:00 pm
For problem 8.13, why is the value of q = 947 kJ negative? I had thought it was positive because the question said that heat was absorbed.
Posted: Fri Jan 19, 2018 6:13 pm
The value of q is negative because the problem states that "the cooling system that surrounds the cylinder absorbs 947 kJ as heat." I think this means that the surroundings absorb the heat, and the actual cylinder itself releases it.
Posted: Sat Jan 20, 2018 1:09 pm
Yes, the surroundings (the cooling system) gain 947 kJ as heat meaning that the system must lose 947 kJ.
Posted: Sat Jan 20, 2018 4:15 pm
In this question the q(of the cylinder) = -w(of the fuel). Which is why when calculating the work of the fuel, the value of q is negative.