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In the Tao of Jeet Kune Do, Bruce Lee defines power as speed times force. — Preceding unsigned comment added by 108.0.237.58 ( talk) 19:44, 9 November 2016 (UTC)
Can the power consumed by a DC circuit with changing voltage (as the battery is depleted) and changing current from times to be defined as follows?
If not, what do I need to change to make it work? -- Oren Hazi 03:34, 29 Jan 2005 (UTC)
Who is so sure that use of power in physics is commoner than that in sociology or mathematics? -- Taku 02:15 May 9, 2003 (UTC)
No, not in wikipedia but generally speaking, of course. -- Taku 03:46 May 9, 2003 (UTC)
The physicists clearly have the primary use of this one. That's the meaning that you would normally assign to "power" unless the context indicated otherwise. Tannin
I think there should be a picture to along with the AC power thingy. The phi is sort of useless without illustrating it. dave 04:35, Feb 22, 2004 (UTC)
The books I have on electrical power use lowercase "i" and "v" for (varying) instantaneous current and voltage, capital "I" and "V" for the constant time-average RMS current and voltage. If no one objects, I'm going to make the article consistent with this. -- DavidCary 20:46, 20 Aug 2004 (UTC)
two things that i know that seem to conflict in my mind:
can we explain why these two things seem intuitively conflicting? - Omegatron 18:54, Sep 2, 2004 (UTC)
I'd like to add the definition of peak power (of a periodic signal) somewhere. Is this article the right place or should it be a page of its own? -- Pgabolde 18:36, 15 Nov 2004 (UTC)
I've proposed that the majority of the content in Power (disambiguation)#Physics be merged to this article. Nothing more is needed on a disambiguation page than enough information to distinguish one possible meaning of a word from the others, yet an article has developed underneath the Physics section of Power (disambiguation). Once the section is merged, a link to this article should remain on the disambiguation page in context that makes it clear that more information about power is available here. -- TantalumTelluride 00:51, 2 November 2005 (UTC)
I think I wrote most of the material that seems to be developing into an article. I thought that there was a need to distinguish between power and energy, but perhaps there isn't so much need to do that on the Power disambiguation page. I will work on cleaning it up. -- C J Cowie 02:37, 2 November 2005 (UTC)
I cut back my previous edits: -- C J Cowie 14:37, 2 November 2005 (UTC)
This merge is now complete. -- TantalumTelluride 16:40, 2 November 2005 (UTC)
One never sees power expressed in elementary units, and this article is no exception. It's J/s, so that would be kg*(m2/s3). I'm surprised to see a power 3 in something so elementary. Is that the reason it is never given? I'd say every article on an SI unit should have an expression in the elementary units right in the intro.
Also, I thought that the more elementary the unit, the simpler it would be. Might this be an indication we're using the wrong basic units? DirkvdM 11:12, 31 January 2006 (UTC)
I agree that every SI unit article should give the unit in terms of SI base units, so I added it to the article on the SI unit Watt. Power is not such an elementary thing. It's actually a rather abstract concept.-- Srleffler 13:39, 31 January 2006 (UTC)
Srleffler, I agree with your caveat about constant force, since the article uses the word "power" in an indefinite sense that doesn't assume an instantaneous measurement. However, if the (total) force on an object is constant, then by Newton's law its velocity cannot be constant, so the formula still addresses only the instantaneous power. I'll try to make that more clear in the article... Melchoir 19:45, 9 February 2006 (UTC)
Is power a scalar or vector. What about energy? I thought that energy flowed and could therefore be considered a vector. Since power is merely the time derivative of energy, doesnt that make it a vector too? Im confused-- Light current 19:36, 27 October 2006 (UTC)
Those formulas are used e.g. in telecommunications.
--
User:Vanished user 8ij3r8jwefi 18:46, 13 May 2008 (UTC)
There used to be a section "Power and strength", which was deleted with this edit. I agree with the deletion and the rationale "there is no evidence that power is confused with strength" in an encyclopedic sense.
However, the fact that the section was there is evidence that at least some editors confuse it. "Power (physics)" is such a fundamental article that it should also be written with such editors or readers in mind. I wrote a comment to that effect in a hidden note, and I realize now it would have been better if I had written it here right away. So if someone feels up to clarifying that confusion, go for it. Maybe I'll do it at some later time. — Sebastian 20:40, 7 December 2008 (UTC)
"Power is a denatured mirroring of force and acceleration in thermal engines' regard."] Marius Pantea feb.2017. — Preceding unsigned comment added by 2A02:A58:843B:A900:FC98:3CBC:9122:C08A ( talk) 22:29, 6 March 2023 (UTC)
I believe that there should be a page created which details the differences between power and energy, primarily by explicitly defining them, including the use of dimensional analysis. The reason that i believe that there should be this specific page is that the terms "power" and "energy" are often used interchangeably in everyday conversation, so someone new to the topic (in its scientific context) could understandably be confused. I would write a page/section about this very issue but i am *very* new to Wikipedia and I don't even know if this idea has been brought up before. Mathiusdragoon ( talk) 22:25, 6 April 2009 (UTC)
The image was very pretty, but there was absolutely no mention of it anywhere in the article. If the image, and more importantly the concept, of the Faraday disk are relevant enough to belong here, then somebody ought to explain the relevance.— PaulTanenbaum ( talk) 14:00, 20 August 2009 (UTC)
Some may find the example I plugged in at the start of the intro a bit out of place. OK. I did feel that a bit of less-technical explanation is in order before the article dives into (eegad!) mathematical formulæ! And my mod scratches user:Mathiusdragoon's itch (see above).— PaulTanenbaum ( talk) 20:24, 29 March 2011 (UTC)
I would like to make some minor changes to the introduction to identify the product of force and velocity, or torque and angular velocity as power. Prof McCarthy ( talk) 16:10, 4 October 2011 (UTC)
I moved the discussion of average power to is own section, and tried to simplify the lead. Prof McCarthy ( talk) 01:52, 10 November 2011 (UTC)
A question arises in this context. If the power is used to accelerate a body from velocity v1 to velocity v2 considering constant acceleration a which velocity should appear in the expression P= F*v= m*a*v, the initial or the final velocity?-- 188.26.22.131 ( talk) 12:21, 1 August 2013 (UTC)
That new section was not explaining how power is force times velocity. So I inserted a more basic section right before that to show simple equations that show this. It's 2016, and the article now clearly communicates that power is the product of force and velocity.--
Tdadamemd sioz (
talk) 04:18, 22 February 2016 (UTC)
Oh, I now see that this relationship was being stated in the section following the one that was being mentioned here.--
Tdadamemd sioz (
talk) 04:22, 22 February 2016 (UTC)
Jc3s5h, thank you for your help with the revisions to the lead. I think it reads very well. Prof McCarthy ( talk) 03:29, 17 November 2011 (UTC)
I tried to smooth out the language for this section on Mechanical power, and found that things got worse and worse. Sorry for the long line of revisions. I hope the result is considered to be an improvement. Prof McCarthy ( talk) 05:48, 21 November 2011 (UTC)
Evidently, one of the two formulae for mechanical advantage (that relating forces or that relating torques) is inverted. As I do not know the definition of mechanical advantage, I do not know which is wrong and can not correct it. Kurt Artindagi ( talk) 07:25, 14 December 2013 (UTC)
I don't think we should be talking about strength. When you say that word to me, I think of units N/m2, not N. It is not a precise term used in physics. The article right now links to Physical strength which does define it as a force, but then goes on to talk about moments about a joint. I think talking about strength when we mean force just muddies the waters. Kendall-K1 ( talk) 12:26, 22 February 2016 (UTC)
I removed this:
This had been linked to Physical strength. That article doesn't define strength at all as far as I can tell, as a force or otherwise. The opening sentence is nonsense: "Physical strength is the measure of an animal's exert of ability on physical objects." Someone changed the link to point to Strength#Physics. There is no information there, it is just a list of possible things "strength" could mean, and none of them are relevant; the various material strengths are measured in force per unit area and don't have anything to do with power. Unless we can find some RS that equates strength to force and says why that's important in understanding power, I don't think this belongs here. Kendall-K1 ( talk) 02:07, 5 October 2016 (UTC)
I find this confusing: "Burning coal produces around 15-30 megajoules per kilogram, while detonating TNT produces about 4.7 megajoules per kilogram... The coal value does not include the weight of oxygen used during combustion, while the TNT number is TNT only." Exploding TNT in a vacuum produces around 4.2 Mj/kg. In air, around 4.7 (from TNT equivalent). In oxygen at 2.5 bar, 15. [1] I think we should change this to say it doesn't include the weight of oxygen from the air for either fuel. Kendall-K1 ( talk) 21:29, 17 October 2016 (UTC)
At the moment electrical power has the following set of equations defining power using Ohm's law:
where
is the resistance, measured in ohms.
But doesn't it make more sense to state Ohm's law in terms of ? Since is the term that is substituted to get the final equation Wrightgw ( talk) 15:05, 18 November 2016 (UTC)
I don't think we need to have "per unit time" at the end of both of the first two sentences. I would go for removing it from the first sentence. Kendall-K1 ( talk) 00:25, 18 September 2017 (UTC)
The dimensions should be L^2*M*T^-3, not L*M^2*T^-3. I'm not sure how to make the edit, though. — Preceding unsigned comment added by 71.238.21.161 ( talk) 06:00, 12 January 2018 (UTC)
I'm not sure it's useful to express power as dW/dt in this section. The typical reader won't know what this means, and the distinction between instantaneous and average power is already discussed in the following section. On the other hand, we already say work/time in the lead, so maybe it's ok. Kendall-K1 ( talk) 15:34, 17 January 2018 (UTC)
I think the very first equation, in the first paragraph of the lead, was better written as "power = work / time". We can add more rigor later in the article, but it was more clear as an introduction when it was written this way. Kendall-K1 ( talk) 00:49, 25 June 2018 (UTC)
The present section "Peak power and duty cycle" needs to be removed/replaced/rethought and retitled. "Duty Cycle" is only meaningful, if at all, in ON/OFF situations, in which the average power is the ON power times the Duty Cycle. 94.30.84.71 ( talk) 14:39, 20 November 2018 (UTC)
Was:
The power of a jet-propelled vehicle is the product of the engine thrust and the velocity of the vehicle.
Changed to:
In classical mechanics, as quantified from a stationary frame of reference, the motive power of a jet-propelled vehicle is the product of the engine thrust and the velocity of the vehicle (note that by this definition, a propelled vehicle hovering at stationary elevation over a gravitational body, where the upward thrust exactly cancels the downward acceleration of gravity, the motive power is zero).
I wasn't quite sure how to get this right, so I settled for making it sound slightly ridiculous.
In the relativistic setting, the observable is acceleration. Acceleration times inertial mass (if known) yields a force (newtons). But then you need to multiply by distance (meters) to obtain energy (joules). I suppose that the occupant of the enclosed elevator could work out a presumptive distance (for the component of acceleration not attributed to gravitational force) but that gets weird in a big hurry (for constant acceleration, your presumed energy output under presumed displacement increases in time, in a manner seemingly dependent on where you assign t=0). Is power actually relative in a way that forces the elevator occupant to look out a window in order to come up with a sane denomination? What am I getting hopelessly wrong here?
In any case, the real issue is what was wrong with the original definition of the motive power of jet propulsion, because I'm personally not entirely satisfied by a definition of power where a stationary hovercraft thruster drowning out conversation for miles around is entirely impotent. — MaxEnt 20:47, 27 January 2021 (UTC)
I have a couple of suggestions for improving the [ [2]] section:
Maxie ( talk) 23:23, 6 March 2021 (UTC)
An editor has identified a potential problem with the redirect Power(physics) and has thus listed it for discussion. This discussion will occur at Wikipedia:Redirects for discussion/Log/2022 October 4#Power(physics) until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Steel1943 ( talk) 18:14, 4 October 2022 (UTC)
This article is written in American English, which has its own spelling conventions (color, defense, traveled) and some terms that are used in it may be different or absent from other varieties of English. According to the relevant style guide, this should not be changed without broad consensus. |
This
level-4 vital article is rated C-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||
|
Accesses of
Power (physics) (left) and
Power (right) articles, last 90 days.
|
In the Tao of Jeet Kune Do, Bruce Lee defines power as speed times force. — Preceding unsigned comment added by 108.0.237.58 ( talk) 19:44, 9 November 2016 (UTC)
Can the power consumed by a DC circuit with changing voltage (as the battery is depleted) and changing current from times to be defined as follows?
If not, what do I need to change to make it work? -- Oren Hazi 03:34, 29 Jan 2005 (UTC)
Who is so sure that use of power in physics is commoner than that in sociology or mathematics? -- Taku 02:15 May 9, 2003 (UTC)
No, not in wikipedia but generally speaking, of course. -- Taku 03:46 May 9, 2003 (UTC)
The physicists clearly have the primary use of this one. That's the meaning that you would normally assign to "power" unless the context indicated otherwise. Tannin
I think there should be a picture to along with the AC power thingy. The phi is sort of useless without illustrating it. dave 04:35, Feb 22, 2004 (UTC)
The books I have on electrical power use lowercase "i" and "v" for (varying) instantaneous current and voltage, capital "I" and "V" for the constant time-average RMS current and voltage. If no one objects, I'm going to make the article consistent with this. -- DavidCary 20:46, 20 Aug 2004 (UTC)
two things that i know that seem to conflict in my mind:
can we explain why these two things seem intuitively conflicting? - Omegatron 18:54, Sep 2, 2004 (UTC)
I'd like to add the definition of peak power (of a periodic signal) somewhere. Is this article the right place or should it be a page of its own? -- Pgabolde 18:36, 15 Nov 2004 (UTC)
I've proposed that the majority of the content in Power (disambiguation)#Physics be merged to this article. Nothing more is needed on a disambiguation page than enough information to distinguish one possible meaning of a word from the others, yet an article has developed underneath the Physics section of Power (disambiguation). Once the section is merged, a link to this article should remain on the disambiguation page in context that makes it clear that more information about power is available here. -- TantalumTelluride 00:51, 2 November 2005 (UTC)
I think I wrote most of the material that seems to be developing into an article. I thought that there was a need to distinguish between power and energy, but perhaps there isn't so much need to do that on the Power disambiguation page. I will work on cleaning it up. -- C J Cowie 02:37, 2 November 2005 (UTC)
I cut back my previous edits: -- C J Cowie 14:37, 2 November 2005 (UTC)
This merge is now complete. -- TantalumTelluride 16:40, 2 November 2005 (UTC)
One never sees power expressed in elementary units, and this article is no exception. It's J/s, so that would be kg*(m2/s3). I'm surprised to see a power 3 in something so elementary. Is that the reason it is never given? I'd say every article on an SI unit should have an expression in the elementary units right in the intro.
Also, I thought that the more elementary the unit, the simpler it would be. Might this be an indication we're using the wrong basic units? DirkvdM 11:12, 31 January 2006 (UTC)
I agree that every SI unit article should give the unit in terms of SI base units, so I added it to the article on the SI unit Watt. Power is not such an elementary thing. It's actually a rather abstract concept.-- Srleffler 13:39, 31 January 2006 (UTC)
Srleffler, I agree with your caveat about constant force, since the article uses the word "power" in an indefinite sense that doesn't assume an instantaneous measurement. However, if the (total) force on an object is constant, then by Newton's law its velocity cannot be constant, so the formula still addresses only the instantaneous power. I'll try to make that more clear in the article... Melchoir 19:45, 9 February 2006 (UTC)
Is power a scalar or vector. What about energy? I thought that energy flowed and could therefore be considered a vector. Since power is merely the time derivative of energy, doesnt that make it a vector too? Im confused-- Light current 19:36, 27 October 2006 (UTC)
Those formulas are used e.g. in telecommunications.
--
User:Vanished user 8ij3r8jwefi 18:46, 13 May 2008 (UTC)
There used to be a section "Power and strength", which was deleted with this edit. I agree with the deletion and the rationale "there is no evidence that power is confused with strength" in an encyclopedic sense.
However, the fact that the section was there is evidence that at least some editors confuse it. "Power (physics)" is such a fundamental article that it should also be written with such editors or readers in mind. I wrote a comment to that effect in a hidden note, and I realize now it would have been better if I had written it here right away. So if someone feels up to clarifying that confusion, go for it. Maybe I'll do it at some later time. — Sebastian 20:40, 7 December 2008 (UTC)
"Power is a denatured mirroring of force and acceleration in thermal engines' regard."] Marius Pantea feb.2017. — Preceding unsigned comment added by 2A02:A58:843B:A900:FC98:3CBC:9122:C08A ( talk) 22:29, 6 March 2023 (UTC)
I believe that there should be a page created which details the differences between power and energy, primarily by explicitly defining them, including the use of dimensional analysis. The reason that i believe that there should be this specific page is that the terms "power" and "energy" are often used interchangeably in everyday conversation, so someone new to the topic (in its scientific context) could understandably be confused. I would write a page/section about this very issue but i am *very* new to Wikipedia and I don't even know if this idea has been brought up before. Mathiusdragoon ( talk) 22:25, 6 April 2009 (UTC)
The image was very pretty, but there was absolutely no mention of it anywhere in the article. If the image, and more importantly the concept, of the Faraday disk are relevant enough to belong here, then somebody ought to explain the relevance.— PaulTanenbaum ( talk) 14:00, 20 August 2009 (UTC)
Some may find the example I plugged in at the start of the intro a bit out of place. OK. I did feel that a bit of less-technical explanation is in order before the article dives into (eegad!) mathematical formulæ! And my mod scratches user:Mathiusdragoon's itch (see above).— PaulTanenbaum ( talk) 20:24, 29 March 2011 (UTC)
I would like to make some minor changes to the introduction to identify the product of force and velocity, or torque and angular velocity as power. Prof McCarthy ( talk) 16:10, 4 October 2011 (UTC)
I moved the discussion of average power to is own section, and tried to simplify the lead. Prof McCarthy ( talk) 01:52, 10 November 2011 (UTC)
A question arises in this context. If the power is used to accelerate a body from velocity v1 to velocity v2 considering constant acceleration a which velocity should appear in the expression P= F*v= m*a*v, the initial or the final velocity?-- 188.26.22.131 ( talk) 12:21, 1 August 2013 (UTC)
That new section was not explaining how power is force times velocity. So I inserted a more basic section right before that to show simple equations that show this. It's 2016, and the article now clearly communicates that power is the product of force and velocity.--
Tdadamemd sioz (
talk) 04:18, 22 February 2016 (UTC)
Oh, I now see that this relationship was being stated in the section following the one that was being mentioned here.--
Tdadamemd sioz (
talk) 04:22, 22 February 2016 (UTC)
Jc3s5h, thank you for your help with the revisions to the lead. I think it reads very well. Prof McCarthy ( talk) 03:29, 17 November 2011 (UTC)
I tried to smooth out the language for this section on Mechanical power, and found that things got worse and worse. Sorry for the long line of revisions. I hope the result is considered to be an improvement. Prof McCarthy ( talk) 05:48, 21 November 2011 (UTC)
Evidently, one of the two formulae for mechanical advantage (that relating forces or that relating torques) is inverted. As I do not know the definition of mechanical advantage, I do not know which is wrong and can not correct it. Kurt Artindagi ( talk) 07:25, 14 December 2013 (UTC)
I don't think we should be talking about strength. When you say that word to me, I think of units N/m2, not N. It is not a precise term used in physics. The article right now links to Physical strength which does define it as a force, but then goes on to talk about moments about a joint. I think talking about strength when we mean force just muddies the waters. Kendall-K1 ( talk) 12:26, 22 February 2016 (UTC)
I removed this:
This had been linked to Physical strength. That article doesn't define strength at all as far as I can tell, as a force or otherwise. The opening sentence is nonsense: "Physical strength is the measure of an animal's exert of ability on physical objects." Someone changed the link to point to Strength#Physics. There is no information there, it is just a list of possible things "strength" could mean, and none of them are relevant; the various material strengths are measured in force per unit area and don't have anything to do with power. Unless we can find some RS that equates strength to force and says why that's important in understanding power, I don't think this belongs here. Kendall-K1 ( talk) 02:07, 5 October 2016 (UTC)
I find this confusing: "Burning coal produces around 15-30 megajoules per kilogram, while detonating TNT produces about 4.7 megajoules per kilogram... The coal value does not include the weight of oxygen used during combustion, while the TNT number is TNT only." Exploding TNT in a vacuum produces around 4.2 Mj/kg. In air, around 4.7 (from TNT equivalent). In oxygen at 2.5 bar, 15. [1] I think we should change this to say it doesn't include the weight of oxygen from the air for either fuel. Kendall-K1 ( talk) 21:29, 17 October 2016 (UTC)
At the moment electrical power has the following set of equations defining power using Ohm's law:
where
is the resistance, measured in ohms.
But doesn't it make more sense to state Ohm's law in terms of ? Since is the term that is substituted to get the final equation Wrightgw ( talk) 15:05, 18 November 2016 (UTC)
I don't think we need to have "per unit time" at the end of both of the first two sentences. I would go for removing it from the first sentence. Kendall-K1 ( talk) 00:25, 18 September 2017 (UTC)
The dimensions should be L^2*M*T^-3, not L*M^2*T^-3. I'm not sure how to make the edit, though. — Preceding unsigned comment added by 71.238.21.161 ( talk) 06:00, 12 January 2018 (UTC)
I'm not sure it's useful to express power as dW/dt in this section. The typical reader won't know what this means, and the distinction between instantaneous and average power is already discussed in the following section. On the other hand, we already say work/time in the lead, so maybe it's ok. Kendall-K1 ( talk) 15:34, 17 January 2018 (UTC)
I think the very first equation, in the first paragraph of the lead, was better written as "power = work / time". We can add more rigor later in the article, but it was more clear as an introduction when it was written this way. Kendall-K1 ( talk) 00:49, 25 June 2018 (UTC)
The present section "Peak power and duty cycle" needs to be removed/replaced/rethought and retitled. "Duty Cycle" is only meaningful, if at all, in ON/OFF situations, in which the average power is the ON power times the Duty Cycle. 94.30.84.71 ( talk) 14:39, 20 November 2018 (UTC)
Was:
The power of a jet-propelled vehicle is the product of the engine thrust and the velocity of the vehicle.
Changed to:
In classical mechanics, as quantified from a stationary frame of reference, the motive power of a jet-propelled vehicle is the product of the engine thrust and the velocity of the vehicle (note that by this definition, a propelled vehicle hovering at stationary elevation over a gravitational body, where the upward thrust exactly cancels the downward acceleration of gravity, the motive power is zero).
I wasn't quite sure how to get this right, so I settled for making it sound slightly ridiculous.
In the relativistic setting, the observable is acceleration. Acceleration times inertial mass (if known) yields a force (newtons). But then you need to multiply by distance (meters) to obtain energy (joules). I suppose that the occupant of the enclosed elevator could work out a presumptive distance (for the component of acceleration not attributed to gravitational force) but that gets weird in a big hurry (for constant acceleration, your presumed energy output under presumed displacement increases in time, in a manner seemingly dependent on where you assign t=0). Is power actually relative in a way that forces the elevator occupant to look out a window in order to come up with a sane denomination? What am I getting hopelessly wrong here?
In any case, the real issue is what was wrong with the original definition of the motive power of jet propulsion, because I'm personally not entirely satisfied by a definition of power where a stationary hovercraft thruster drowning out conversation for miles around is entirely impotent. — MaxEnt 20:47, 27 January 2021 (UTC)
I have a couple of suggestions for improving the [ [2]] section:
Maxie ( talk) 23:23, 6 March 2021 (UTC)
An editor has identified a potential problem with the redirect Power(physics) and has thus listed it for discussion. This discussion will occur at Wikipedia:Redirects for discussion/Log/2022 October 4#Power(physics) until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Steel1943 ( talk) 18:14, 4 October 2022 (UTC)