A double-A (AA) rechargeable battery is rated at 1.2V, 2100mAh (mili-amp hours)
1- how many coulombs of charge can this battery hold?
2- how many joules of energy are stored in the battery?
3- if the battery is used to power a water pump at 80% efficiency, how much water could it pump while maintaining a pressure of 100 J/m^3?