Ok, but when it comes to electrical energy nobody uses “watt seconds” in the real world. Devices use hundreds of watts, and run for minutes and hours. Dividing by 3.6 million isn’t exactly easy mental math to get the unit (kWh) we all see on our electric bills.
Also, you’ll notice that I specifically mentioned electrical energy. Electrical power is almost universally measured in watts, the product of voltage and current, not joules per second (even if that’s the same thing). So going from instantaneous power measurements to energy accumulated over time, it’s not crazy to use the term “watt second” the way one would use “kilowatt hour”… Even if that’s also called a “Joule”
But they don’t use that either in the context of real-world electricity usage. Maybe in the middle school classroom setting, when you can make up the numbers you work with, but when I’m trying to quantify how much energy something uses at home I multiply how many watts it uses by now many hours it’s running. Divide that by 1000 for kilowatt-hours, and multiply by $.11 to know the cost to do it at home. If I need to do a multiplication/division of 3.6 million when nobody else is, something’s not right.
Similarly, a meter is a standard unit for length, but we don’t use it when measuring the distance to different galaxies because light-years are more practical at that scale. If you start using meters you’d get some funny looks, just as I’m feeling for joules instead of kilowatt-hours. But you know, “almost a kilowatt-hour” makes for a pretty boring headline.
Ok, but when it comes to electrical energy nobody uses “watt seconds” in the real world. Devices use hundreds of watts, and run for minutes and hours. Dividing by 3.6 million isn’t exactly easy mental math to get the unit (kWh) we all see on our electric bills.
Joules. They don’t say watt seconds because they say joules.
Also, you’ll notice that I specifically mentioned electrical energy. Electrical power is almost universally measured in watts, the product of voltage and current, not joules per second (even if that’s the same thing). So going from instantaneous power measurements to energy accumulated over time, it’s not crazy to use the term “watt second” the way one would use “kilowatt hour”… Even if that’s also called a “Joule”
But they don’t use that either in the context of real-world electricity usage. Maybe in the middle school classroom setting, when you can make up the numbers you work with, but when I’m trying to quantify how much energy something uses at home I multiply how many watts it uses by now many hours it’s running. Divide that by 1000 for kilowatt-hours, and multiply by $.11 to know the cost to do it at home. If I need to do a multiplication/division of 3.6 million when nobody else is, something’s not right.
Similarly, a meter is a standard unit for length, but we don’t use it when measuring the distance to different galaxies because light-years are more practical at that scale. If you start using meters you’d get some funny looks, just as I’m feeling for joules instead of kilowatt-hours. But you know, “almost a kilowatt-hour” makes for a pretty boring headline.