Subject: How come when you rub steel wool to 9 volt battery it starts on fire?

I know this works because we did it in boy scouts to help learn about wilderness 
survival. I know it has something to do with electricity, heat and energy. I 
just can't figure it out. If you can give me an idea or tell me where to go on 
the internet (I have been serching for hours.) Thank you very much for your 
help.  Jarett

Re: How come when you rub steel wool to 9 volt battery it starts on fire?