Calculating Power Output of a Battery Bank Circuit with Multiple Loads

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ABR124
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Homework Statement



A 48 V DC wind turbine is hooked up to charge a battery bank consisting of four 12 V batteries in series. The wind is not blowing, but the batteries must supply 2 loads. One is a light bulb, rated at 175 W at 48 V; the other is a heater, rated 1000 W at 48 V. The loads are in parallel. The batteries may be constant 12V voltage sources, with an internal series resistance of 0.05 ohm each. How much power is actually supplied to the loads?
(Ignore the effect of temperature on resistance of filament and heating Elements)

Homework Equations



I'm assuming ohms law but don't know where start

The Attempt at a Solution



I don't know where to start with this question or what variables I'm even solving for. Here is a diagram I drew of the circuit.
[PLAIN]http://img121.imageshack.us/img121/7571/windquestion1.jpg
 
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Discussion

You can work out the resistance of the combined load (1000 watts plus 175 watts).
Like this:
Power = E^2 / R
so R = E ^ 2 / Power.

Then put the combined series resistance of each battery ( 4 times 0.05 ohms) in series with this load resistance.

Then you can work out the current. I = 48 volts / total resistance of batteries plus load.

This current passes through the combined resistances of the load so you can work out the power in the load by
Power = I ^ 2 * R.
 
Thank you for your help

One question though, when working out the final step of this problem to find the power of the combined loads, do I use the total resistance, or just the load resistance?