Why are Watt Hours not Watts per Hour? Are they the same thing?
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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.
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.
A watt is a measure of power, which is defined as energy per unit of time: e/t . So, a watt-hour (or, more typically, a “kilowatt-hour”) is a measurement of energy: e/t * t.
There’s also “watt-seconds,” which have another name: Joules. So, a watt-hour is 3600 watt-seconds, or 3600 joules.
So, why do we use watt-hour, or kilowatt-hours? Mainly because it’s more useful: a A 100 watt light bulb uses 100 watt-hours of energy every hour. Leave it on for 10 hours, and you have one kilowatt-hour. If you measured that in joules, then it would be 3.6M joules over that same 10 hour period.
Watt-hours and watts-per-hour are not the same thing. It’s the difference between saying that “a job consumes 10 man-hours” v. saying “it consumes 10 men per hour.” (I dunno, maybe it’s a job with a really high fatality rate.)
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-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 is a unit of energy.
A watt per hour /second It is a unit of power that is energy usage per unit of time
and 1 hour =3600 second
1 watthour = 1 joule /second * 3600 second =3600 joule
1 watt-second is the same as 1 joule
1 watt per hour = 1 joule /second / 3600 second =1/3600 joule/second^2
That is a rate of change of power. So 1 watt per hour means the power usage increases 1 watt every hour. So a if a device start to use 40 watts is will use 41 watts after 1 hour, 42 after to, and so on.
You can compare that to the moment. I will use second not hour it just remove constant that is multiple of 3600
The distance traveled will be equal to the energy.
So 1 meter is like 1 joule =1watt-second
The speed will be the power
so 1meter per second is like 1 watt = 1 joule/second.
The acceleration will be like the watt per hour
So 1 meter/second ^2 is like 1watt/second = = 1 joule/second^2
So the watt-hour is the speed and watt/hour is the acceleration. It is quite a different concept.
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.
A watt is a measure of power, which is defined as energy per unit of time: e/t . So, a watt-hour (or, more typically, a “kilowatt-hour”) is a measurement of energy: e/t * t.
There’s also “watt-seconds,” which have another name: Joules. So, a watt-hour is 3600 watt-seconds, or 3600 joules.
So, why do we use watt-hour, or kilowatt-hours? Mainly because it’s more useful: a A 100 watt light bulb uses 100 watt-hours of energy every hour. Leave it on for 10 hours, and you have one kilowatt-hour. If you measured that in joules, then it would be 3.6M joules over that same 10 hour period.
Watt-hours and watts-per-hour are not the same thing. It’s the difference between saying that “a job consumes 10 man-hours” v. saying “it consumes 10 men per hour.” (I dunno, maybe it’s a job with a really high fatality rate.)
A watt is a measure of power, which is defined as energy per unit of time: e/t . So, a watt-hour (or, more typically, a “kilowatt-hour”) is a measurement of energy: e/t * t.
There’s also “watt-seconds,” which have another name: Joules. So, a watt-hour is 3600 watt-seconds, or 3600 joules.
So, why do we use watt-hour, or kilowatt-hours? Mainly because it’s more useful: a A 100 watt light bulb uses 100 watt-hours of energy every hour. Leave it on for 10 hours, and you have one kilowatt-hour. If you measured that in joules, then it would be 3.6M joules over that same 10 hour period.
Watt-hours and watts-per-hour are not the same thing. It’s the difference between saying that “a job consumes 10 man-hours” v. saying “it consumes 10 men per hour.” (I dunno, maybe it’s a job with a really high fatality rate.)
The simple answer is that Watts are already a measurement of rate.
1Watt = 1Joule/ Sec
So a watt-second is a count of energy
Joule/Sec * Sec = just Joules
A watt per second is like a measurement of acceleration – how “fast” is my rate changing?
Watt/Sec = Joules/Sec/Sec.
Using hours is just saying “3600 seconds” in the above math.
Think of it like “mph”, if mph was it’s own unit.
1mph * 1hour = 1 mile.
1mph/1hour = I sped up from 50 mph to 51 mph over the course of an hour.
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