5-4. It will be useful for you to know that the specific heat of water is
4186 J/kg-degrees C.
6-3b. The answer should be -18.0, -20.0 V.
6-4. In the figure, change 10.0 ohms to 10.0 V and change
20.0 ohms to R. Note that the algebra in this problem is challenging.
I advise you to apply the loop rule to the top loop and to the bottom
loop.