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Postby Connie2I » 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.

Lisa Tang 1C
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Re: 8.13

Postby Lisa Tang 1C » 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.

Julie Steklof 1A
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Re: 8.13

Postby Julie Steklof 1A » 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.

Charles Ang 1E
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Re: 8.13

Postby Charles Ang 1E » 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.

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