Final answer:
The unit of work or energy equal to that expended by one kilowatt in one hour is called the kilowatt-hour (kWh), commonly used to measure electricity usage. It can be converted into joules, with 1 kWh being equal to 3.6 million joules.
Step-by-step explanation:
The name of the unit of work or energy that is equal to that expended by one kilowatt in one hour is the kilowatt-hour (kWh). This measurement of energy is commonly used to calculate electric energy consumption and consequently the cost of operating electrical appliances. To understand this, consider the relationship E = Pt where E is energy, P is power in kilowatts, and t is time in hours. For instance, the energy expended by an appliance that uses 60 watts over a period of 1000 hours is calculated as E = (60 W)(1000 h) = 60,000 W . h, or 60 kWh. The kilowatt-hour can also be converted into joules, where 1 kWh is equivalent to 3.6 million joules (J), due to the conversion where 1 kW equals 1,000 J/s and 1 hour equals 3,600 s.