Chapter 6 - Problems - Page 231: 72

1 kilowatt-hour is 3.6 MJ

1 kilowatt-hour is the amount of energy that would be used if 1 kilowatt of power was used for one hour. We can find the amount of energy that would be used: $Energy = (Power)\times (Time)$ $Energy = (1000~W)\times (1~hour)$ $Energy = (1000~J/s)\times (3600~s)$ $Energy = 3.6\times 10^6~J$ $Energy = 3.6~MJ$ Therefore, 1 kilowatt-hour is 3.6 MJ.