The battery on your car has a rating stated in ampere-hours that permits you to estimate the length of time a fully charged battery could deliver any current before discharge. Approximately how much energy is stored by a 50 A-hour 12-V battery? Assuming 100% efficient energy conversion, how much water stored behind a 30-m high hydroelectric dam would be required to charge the battery? (For the 2nd part of this question, you might need to review your concepts in potential energy and energy transfer)