Why are Watt Hours not Watts per Hour? Are they the same thing?
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Watt hours is multiplying power and time to give an energy: it’s energy divided by time (power) times time, to give energy.
When we say “<something> per <something else>”, it means the first thing divided by the second. So watts per hour would have units of energy divided by time *squared* and would be something like how fast some power is changing. It’s basically going the opposite direction of watt-hours.
A nice analogy that might help is thinking about energy as being like distance. In that analogy, power is like distance per time, or speed. To get total distance from some speed, you need to multiply the speed (power) by how long you have been going that speed (time) to give total distance. Watt-hours as a unit would be kind of like mph-hours or something. It sounds weird, but it’s just a distance. Speed per time is an *acceleration* in this analogy and tells us how fast our speed is changing. Acceleration has units of distance per time squared, just like watts per hour would have units of energy per time squared and would tell us how fast some power is changing.
Watt Hours are units of energy, power multiplied by time.
Watts are a unit of power, energy divided by time.
Watts per hour doesn’t really make all that much sense, unless you mean the change in power output over time.
Watts per hour is a bit redundant. Watts is a measurement of energy used per second with the units of joules and seconds. Watts = (Joules/seconds). Watt hours is a total amount of energy used. If we take the formula for Watts and multiply by hours(3600 seconds) the result is joules or energy.
Watts is power – which is the time rate of energy….meaning it’s energy divided by time.
If you have a 100 watt light bulb, that tells you how much energy per unit of time you are using – or the energy rate.
If you want to know how much total energy you have used in a time period, you have to multiply the energy rate x time….if you leave a 100 watt light on for 1 hour, you have consumed 100 watt-hours….or 0.1 kw-hr.
Dividing watts (which is energy over time) by time again doesn’t have much practical use.
Watt-hour is watts * hours. This is a unit of energy.
Watts per hour is watts / hours. This is a unit of the rate of the rate of energy consumption.
After converting hours to seconds these units would be equivalent to:
Watt-hours –> Joules
Watts per Hour –> Joules per second per second or Joules / second^2. You might look at this as the acceleration of energy usage.
Watt-hours is the total electrical energy supplied if a watt is sustained for one hour, or 3600 joules.
A watt is a rate of energy transfer. It doesn’t make much sense to say “watts per hour” since you are saying a rate per unit of time. Like “mph per hour”. In this case you would essentially be describing a rate of acceleration of energy transfer instead of watt-hours which is a specific amount of energy.
Watt Hours are a unit of watts multiplied by hours. Watts *per* hour would be a unit of watts *divided* by hours, which would obviously produce a very different result.
We are more familiar with the phrase “per hour” because we commonly use it to measure speed in miles or kilometers per hour. But you might have heard a comparable unit to Watt Hours used in a business setting when people talk about man hours. The idea being if ten people worked on a task for a 40 hour businesses week, then the task was completed in 40 hours but took 400 total man hours to complete (i.e. it would theoretically take 400 hours of work for one person).
Watt Hours are a unit of watts multiplied by hours. Watts *per* hour would be a unit of watts *divided* by hours, which would obviously produce a very different result.
We are more familiar with the phrase “per hour” because we commonly use it to measure speed in miles or kilometers per hour. But you might have heard a comparable unit to Watt Hours used in a business setting when people talk about man hours. The idea being if ten people worked on a task for a 40 hour businesses week, then the task was completed in 40 hours but took 400 total man hours to complete (i.e. it would theoretically take 400 hours of work for one person).
Watts per hour is a bit redundant. Watts is a measurement of energy used per second with the units of joules and seconds. Watts = (Joules/seconds). Watt hours is a total amount of energy used. If we take the formula for Watts and multiply by hours(3600 seconds) the result is joules or energy.
A watt is already a rate, it’s one joule per second. A watt-hour is one watt *times* one hour, or one watt for one hour, or 3600 joules.
Imagine an alternate universe where instead of measuring distance in miles and speed in miles per hour, we just had a unit of speed, let’s call it steve. In your car, you have a speedometer that measures your speed in steve, so very slow might be 10 steve, but very fast might be 100 steve.
If you got in your car and drove at 50 steve for one hour, how far would you have gone? In this alternate universe we don’t have a unit of distance, so we’ll say that you went 50 steve-hours. And if you turned around and went back but only went as fast as 5 steve, it would take 10 hours to go the same 50 steve-hours of distance.
That’s how watts work. Watts are energy over time, watt-hours are energy.
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