SageBrush
REJECT Fascism
At this rate someone will write about the viral load in watts
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Prediction: Coal has fallen. Nuclear is next then Oil.
- Thread starter nwdiver
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At this rate someone will write about the viral load in watts
SageBrush
REJECT Fascism
Obviously, it's the tridecahexahectakilojoule.
In the UK people just used to refer to "units" of electricity until people eventually started talking about kWh.
dgpcolorado
high altitude member
Not clear on your point. It is true that joule, watt, as well as volt, are all derived from base units.
My hypothesis is that a century ago an electrical device's power was rated in watts, rather than J/s, and that led to measuring energy in Wh (and kWh) rather than joules.
I wonder if some of the misuse of kW and kWh here at TMC might be due to autocorrect errors that are missed?
It is clear, however, that some are genuinely fuzzy on the difference between the units. I get as annoyed as others at the misuse. It isn't being pedantic, misuse of kW and kWh leads to genuine confusion IME.
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My hypothesis is that electricity companies care about use of power, so charge you for power x time.
mspohr
Well-Known Member
When comparing different sources of energy, it's best to use neutral units such as Joules rather than source specific units such as kWh, BTU, etc.
SageBrush
REJECT Fascism
Sorry, I meant the Amp
I think most people can grasp units of amount, and amount per time
By extension -- energy, and energy per time.
Or work, and work per time
The base units of Kg, distance and seconds plug in nicely.
But Amps are a base unit and few people can translate volts*Amps into energy per time using base units
I know that my wife chokes on these ideas because she cannot shake the desire to treat 'watt' as an amount
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TheTalkingMule
Distributed Energy Enthusiast
I believe I actually started a thread on this topic simply because it's a big stumbling block for homeowners trying to buy solar. Personally, I think the average bloke could wrap his head around the "number of elon's(©) produced annually" much more easily thank kilowatt-hours.
dgpcolorado
high altitude member
More generally, most people are not well-versed in the hard sciences, even if some did take basic classes in high school (or college). It is hardly surprising that this stuff is a mystery to that large population, some of whom drive electric cars without understanding concepts of power versus energy.
This helped me to conceptualize Joules, Watts and Watt-Hours. Maybe somewhat oddly I had a hard time conceptualizing what a 'Joule' was. Made me realize how contrived kWh is... the 'h' basically mutates a unit of power into a unit of energy.
I blame the fact that energy needs a time component and time isn't base 10. So a Watt-Hour is 3600 Joules because there's 3600 seconds in a hour. If time was base 10 you could use Joules as easily as kWh. Joules and Watt-Hours is like the metric equivalent of inches and feet
I blame the fact that energy needs a time component and time isn't base 10. So a Watt-Hour is 3600 Joules because there's 3600 seconds in a hour. If time was base 10 you could use Joules as easily as kWh. Joules and Watt-Hours is like the metric equivalent of inches and feet
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You call it mutation, I call it math.
In your terms, I could argue that it's actually reversing the mutation.
Maybe... but Watt is a unit of Power and Joule is a unit of Energy. Just seems a little weird to use a unit of power and time to express energy instead of just using a unit of energy.
It would be like selling Gasoline by the HPh. $0.04 / HPh
Or if you said an Engine was 300k J/s in stead of 400 HP. We have different units for power and energy for a reason. It would be possible to express all energy and power as J and J/s or Wh and W but that just gets ungainly.
mspohr
Well-Known Member
That's the point. Time has no business being part of an energy unit.Maybe... but Watt is a unit of Power and Joule is a unit of Energy. Just seems a little weird to use a unit of power and time to express energy instead of just using a unit of energy.
It would be like selling Gasoline by the HPh. $0.04 / HPh
Or if you said an Engine was 300k J/s in stead of 400 HP. We have different units for power and energy for a reason. It would be possible to express all energy and power as J and J/s or Wh and W but that just gets ungainly.
.... Energy is defined as Work / Time. Time is an inseparable part of energy. A Joule is;
I think that's why I had such a hard time conceptualizing a Joule. I didn't really realize that there IS a time component to a Joule. That's why you have to add the 'h' to kWh. The 1 h 'cancels out' the 3600 seconds in a Joule so you can express a unit of power (kW) as a unit of energy (kWh).
Kinda funny if you look at how these units are derived. A Joule is defined by moving a kg 1m so 'kg' is a basis for a Joule. A kg is now based on Planks Constant which is ~6.6E-34 (J)(s). So Js are based on kg and kg are based on Js....
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SageBrush
REJECT Fascism
You might find it amusing to start from Newton's observation that an object traveling at a constant velocity has no force applied. The converse then is a force acting on an object (in the same direction as travel) must result in object acceleration, meter per second per second.
Work is defined as force over a distance, so we end up with meter * (meter per second per second)
Yeah... I'm still working on conceptualizing force. Amps, Volts and Watts all 'mean' something to me. Newtons not so much...
mspohr
Well-Known Member
Interesting that Newton's insight into gravity - Apple falling from the tree - came while he was quarantined from the plague in his country home and was out sitting under a tree. Might not have happened otherwise.
mspohr
Well-Known Member
SageBrush
REJECT Fascism
Conceptualizing ?!
This is a Tesla forum. We have a philosophical requirement that all reasoning begin with first principles
juliusa
Active Member
They care about the power too. They charge a load factor for commercial users.
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