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# Potential energy of suspended mass expressed in kWh

#### CircutScoper

Mar 29, 2022
300
It does not look better to me. Superstitiously, I have avoided horse power units. I prefer to work in metric terms where values relate to natural constants and not arbitrary thumb length.

Not arbitrary? Well, let's see...

The meter was originally defined to be 1/40.000,000th of the polar circumference of the Earth -- which varies arbitrarily with longitude.
The kilogram was defined from 1/10th of that. cubed, times the density of water -- which varies arbitrarily with temperature..
And the second from 1/86400 of the length of a Solar day, which varies arbitrarily with the date.

Anyone seeing anything fundamental in any of that, please raise your thumb.

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#### HANKMARS

Jul 28, 2019
498
29.4kJ = 0.00817 kWhr to raise a metric ton three meters against 9800 Newtons of gravitational force is correct. The takeaway is that 1kWhr = 3.6MJ is a buttload (technical physics term) of energy that could life 1000kg 367 meters.
I traditional units, 1 kg is one one-thousands of a tonne (tonne = metric ton = Mg )

#### CircutScoper

Mar 29, 2022
300
I assume that your 1000kg is = to 1000 grams and is not = to a Mg (a tonne)
No. 1000kg = 1Mg and 29,400J (0.00817kWh) can lift it 3m against the force of gravity -- provided you do it very slowly.

Do it fast, and you'll need extra Joules to produce the necessary kinetic energy.

#### HANKMARS

Jul 28, 2019
498
Not arbitrary? Well, let's see...

The metre was originally defined to be 1/40.000,000th of the polar circumference of the Earth -- which varies arbitrarily with longitude.
The kilogram was defined from 1/10th of that. cubed, times the density of water -- which varies arbitrarily with temperature..
And the second from 1/86400 of the length of a Solar day, which varies arbitrarily with the date.

Anyone seeing anything fundamental in any of that, please raise your thumb.
I sincerely assumed the length of a metre was based on emission frequency wavelength of an element. I believe the exact water temp when determining a gram mass is listed in that particular method of mass determination. I might agree that a second is in a sense, an averaged value. However, the basis of time is definitely based on cosmic events. I think it is derived by representing one revolution of Earth on its axis graphically by a circle. 360 degrees of arc reps a day. 86,400 / 3600 = 24. I'll go down that rabbit hole later.

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#### CircutScoper

Mar 29, 2022
300
I sincerely assumed the length of a metre was base on emission frequency wavelength of an element.

In the middle of the French revolution when the metre was defined in between sessions of lopping off heads, krypton wasn't even yet known to exist.

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#### CircutScoper

Mar 29, 2022
300
I sincerely assumed the length of a metre was based on emission frequency wavelength of an element. I believe the exact water temp when determining a gram mass is listed in that particular method of mass determination.

Didn't work. So they had to go with an arbitrary lump whittled out of platinum.

Meanwhile, the fundamental fact in play here is that weights and measures have nothing to do with science. They're nothing but politics.

https://www.livescience.com/26017-kilogram-gained-weight.html#:~:text=To solve the problem, scientists,the definition of the kilogram.

The kilogram was first adopted as an international standard at the Convention of the Metre in 1875.At that time, scientists were frustrated that there was no consistent, standard way to measure mass with high precision.

To solve the problem, scientists created a cylindrical hunk of mass called the international prototype kilogram (IPK) from platinum and platinum-iridium alloy. The cylinder, which weighs approximately 2.2 pounds (1 kilogram), is the definition of the kilogram. The kilogram is one of seven standard international base units of measurement.

In the 1880s, about 40 of these prototype kilograms were distributed to countries that signed the Metre Convention, said study co-author Peter Cumpson, a metrologist at Newcastle University in the U.K.

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#### Bluejets

Oct 5, 2014
7,098
Well then, if friction causes heat, how long does it take a monkey to screw a bucket of water (10 litres) to boiling point.

#### CircutScoper

Mar 29, 2022
300
Well then, if friction causes heat, how long does it take a monkey to screw a bucket of water (10 litres) to boiling point.

In nanoseconds, fortnights, or parsecs?

#### HANKMARS

Jul 28, 2019
498
No. 1000kg = 1Mg and 29,400J (0.00817kWh) can lift it 3m against the force of gravity -- provided you do it very slowly.

Do it fast, and you'll need extra Joules to produce the necessary kinetic energy.
So you are expressing the m in PE = mgh in SI units not in traditional units where the mass base unit is the gram and not the kg. Hence, 1000 x 9.8 x 3 = 29,400. However, in your written equation, 1000kg = 1Mg you are expressing mass as grams. How do you determine which value for m you will be using?

#### CircutScoper

Mar 29, 2022
300
So you are expressing the m in PE = mgh in SI units not in traditional units where the mass base unit is the gram and not the kg. Hence, 1000 x 9.8 x 3 = 29,400. However, in your written equation, 1000kg = 1Mg you are expressing mass as grams. How do you determine which value for m you will be using?

First tell me what value you're using for g, which varies from 9.798 at the equator to 9.863 at the poles.

#### Bluejets

Oct 5, 2014
7,098
In nanoseconds, fortnights, or parsecs?

Well known comparison would suffice....

#### HANKMARS

Jul 28, 2019
498
29.4kJ = 0.00817 kWhr to raise a metric ton three meters against 9800 Newtons of gravitational force is correct. The takeaway is that 1kWhr = 3.6MJ is a buttload (technical physics term) of energy that could life 1000kg 367 meters.

Let me convert a little. 0.00817kWh = 8.17Wh. Matching quantities pretty sure. One of my LED light bulbs draws 9W. Therefore, the energy to elevate a tonne 3 meters, in an hour, is equal to the power required to illuminate my 9W bulb for one hour, approximately. Seems unfair. I request that I operate the hand crank generator that powers my LED light for an hour and leave the hand operated mechanism lifting a tonne 3 meters in an hour, to you. I can see maybe that we may both exert about the same amount of work. With a 2 ton chain hoist, you could readily move a tonne 3 meters in height within an hour. Hmmm. I need to ponder this a few moments.I use many AA size NI-MH 1.2V batteries. Their rating is 2800mAh. I can calculate Wh of battery by multiplying battery voltage by Ah rating. 2.8Ah X 1.2 V = 3.36Wh. 3.36 / 1000 = 0.00336kWh. Therefore, 3 AA batteries have the required energy to raise a tonne 3 meters. A world of 100% efficiency energy transfer devices might prove that true. Gots ta ruminate a spell on dat un..

#### HANKMARS

Jul 28, 2019
498
First tell me what value you're using for g, which varies from 9.798 at the equator to 9.863 at the poles.
9.8

#### CircutScoper

Mar 29, 2022
300
I sincerely assumed the length of a meter was based on emission frequency wavelength of an element. I believe the exact water temp when determining a gram mass is listed in that particular method of mass determination. I might agree that a second is in a sense, an averaged value. However, the basis of time is definitely based on cosmic events. I think it is derived by representing one revolution of Earth on its axis graphically by a circle. 360 degrees of arc reps a day. 86,400 / 3600 = 24. I'll go down that rabbit hole later.

Rabbit hole is right, because the time required for the Earth to revolve one complete turn on its axis is actually only 86,164 seconds = the length of the sidereal day. 86,400 seconds, by contrast, is the length of the mean solar day, which is really only an optical illusion: E.g.: sunrise.

#### CircutScoper

Mar 29, 2022
300

Seems arbitrary. 9.863 rounds off to 9.9.

#### HANKMARS

Jul 28, 2019
498
Seems arbitrary. 9.863 rounds off to 9.9.
What percentage of error are we talking over entire g range discrepancy seeings how discrepancy is a magnitude of 3 away from more result determining values.

#### HANKMARS

Jul 28, 2019
498
Rabbit hole is right, because the time required for the Earth to revolve one complete turn on its axis is actually only 86,164 seconds = the length of the sidereal day. 86,400 seconds, by contrast, is the length of the mean solar day, which is really only an optical illusion: E.g.: sunrise.
Probably matters to missile guidance systems but that's not my concern.

#### CircutScoper

Mar 29, 2022
300
Probably matters to missile guidance systems but that's not my concern.

It mattered to Galileo, because the reason for the difference is the interesting (to some) fact that the Earth orbits the Sun rather than the other way 'round. Yakking about it almost got him burned at the stake.

And I thought you said you get interested when "values relate to natural constants."

Oh well. Guess that was somebody else.

#### CircutScoper

Mar 29, 2022
300
View attachment 55330

...I request that I operate the hand crank generator that powers my LED light for an hour and leave the hand operated mechanism lifting a tonne 3 meters in an hour, to you...

I think I rather leave that to a horse, then the job oould be done in ~36 seconds -- give or take.

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#### bertus

Moderator
Nov 8, 2019
3,399
Hello,

The meter was originally defined to be 1/40.000,000th of the polar circumference of the Earth -- which varies arbitrarily with longitude.
The kilogram was defined from 1/10th of that. cubed, times the density of water -- which varies arbitrarily with temperature..
And the second from 1/86400 of the length of a Solar day, which varies arbitrarily with the date.

Here are the SI defenitions, from the posted PDF:

Bertus

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