# Homework Help: Stored energy in a battery

1. Jan 16, 2008

### PowerIso

1. The problem statement, all variables and given/known data
A certain lead acid storage battery has a mass of 30kg, Starting from a fully charged state, it can supply 5 amperes for 24 hours with a terminal voltage of 12 V before it is totally discharged. a If the energy stored in the the fully charged battery is used to lift the battery with 100% efficiency what height is attained? Assume that the acceleration due to gravity is 9.88 m/s/s and is constant with height. b. If the energy stored is used to accelerate the battery with 100% efficiency what velocity is attained. C Gasoline contains about 4.5 x 10^7 j/kg. Compare this with the energy content per unit mass for the fully charged battery.

2. Relevant equations

3. The attempt at a solution

I don't have an attempt to the solution manly because I am at lost to where to begin. I've read the section this question is referring to over and over again and I can't seem to get any closer to solving this problem. Can anyone please give me a hint on how to solve such a problem?

2. Jan 16, 2008

### chroot

Staff Emeritus
It's just an energy problem. Start by calculating how much energy is delivered in total by a 5 A current at 12 V over 24 hours. Then, figure out the equivalent altitude where the 30 kg battery has that same amount of gravitational potential energy as was released in the form of electricity.

- Warren

3. Jan 16, 2008

### PowerIso

Thanks a lot. I ended up with 17.6 km for the height and 587 m/s for the velocity question. I'm still confused on part c. It's been about 3 years since i've taken physics I and II, so i'm trying to recall old information, but it's hard.