Posted by **Stefan** on Saturday, December 4, 2010 at 6:24pm.

A nuclear power plant has an electrical power output of 1200 MW and operates with an efficiency of 31%. If excess energy is carried away from the plant by a river with a flow rate of 1.0 x 10^6 kg/s, what is the rise in temperature of the flowing water?

- Physics -
**MathMate**, Saturday, December 4, 2010 at 6:56pm
Energy converted to heat

= 1200*10^6W/0.31

=3.87*10^9W

=3.87&10^9 j/s

Now divide by 4.18 to convert to cal/s

and divide by the mass of water (in grams) per sec. to get the increase in temperature in °C.

- Physics -
**Stefan**, Saturday, December 4, 2010 at 7:11pm
Thanks for your help. For the answer I got it to be 0.925837321 by following your directions. When I submitted it to my online homework it said the answer was wrong and off by more than 10%.

- Physics -
**bobpursley**, Saturday, December 4, 2010 at 7:16pm
Good Lord. How did you get .925 from 3.87E9/4.18 ?

- Physics -
**Stefan**, Saturday, December 4, 2010 at 7:22pm
By taking 3.87E9/4.18 then dividing it by the flow rate of the water (1.0E6 kg/s = 1.0E9 g/s)

- Physics -
**bobpursley**, Saturday, December 4, 2010 at 7:29pm
I see the error.

Energy produced+heat=total

but it is given that energy produced/total is .31, which means heat produced is .69 of energy produced, so..

heat produced= .69*1200*10^6W/0.31

Now do the conversions.

check my thinking.

- Physics -
**Stefan**, Saturday, December 4, 2010 at 7:32pm
Thanks for your help! I got the correct answer

- Physics -
**MathMate**, Saturday, December 4, 2010 at 7:49pm
Sorry Stefan, and thank you Bob!

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