This isn't actually a homework/schoolwork question, but all the stickies on the other boards say that anything that is a school-work *type* question should go here. Not sure if this qualifies, but I figured I'd err on the side of caution. I took physics II last year and now I'm trying to do a little electronics project -- and to my consternation it appears I didn't learn how to compute something pretty simple!(adsbygoogle = window.adsbygoogle || []).push({});

Suppose I know the total resistance of components in a circuit. In my case it's R = 2292 Ohms. And suppose I've got a battery with an EMF of 14.8 V. How would I find out the time it would take for my battery to run down? Do I need more information? It seems my most relevant equation is that for power delivered to a resistor: [tex] P = V_{ab} = I^2R = (V_{ab})^2 /R [/tex]

However, I don't want the power, which is the work/time, I just want the time. I don't know how I would find out the work that's done. the circuit elements are four motors which are labeled "90W", but I don't know if that means they require 90W every second, or what. How do I find a "t" variable in this equation that I can solve for?

Thanks!

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Homework Help: How long will a battery last?

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