Question

One kilowatt hour (kWh) is the amount of work or energy generated when one kilowatt of power is supplied for a time of one hour. A kilowatt hour is the unit of energy used by power companies when figuring your electric bill. Determine the number of joules of energy in one kilowatt hour.

Answer 1

The definition of Power tells us that it is the amount of Energy supplied during a certain period of time.

In this case 1 kWh is the amount of energy released during a period of 60 minutes to replace a given task.

In practical terms 1kW hour is the equivalent of one thousand Watts, that is

$P = \frac{E}{t}$

Where

P = Power

E = Energy

t = time

The power is equal to 1000W or 1000J/s through a hour, then

$E = Pt$

$E = 1000\frac{J}{s}1hour (\frac{3600s}{1hour})$

$E = 3.6*10^6J$

Therefore the number of Joules of energy in one Kilowatt hour are $3.6*10^6J$