Talk:Speed

message: :The following highlights current issues. Feel free to either add the issues you've identified, or to strike them as they've been resolved.
WikiProject Physics' Reviewing Cheatsheet 06:44, 15 July 2008 (UTC)
thread_title: Reviewing Cheatsheet

message: Speed is the essence of things. Such a common expression. 
It all started with my having to help my daughter write an article on "Slow down, you are moving too fast". I have read a book by an American Author called James Gleick - not sure if I got the name correct. He wrote a book called Speed. He is also the author of a book called "Chaos". I am looking for this book. Wonder if anyone can let me know the correct name of the author.
How comes speed and acceleration have no direction _ They are vectors and definitely they have directions.
If you want to know anything about motin or otherwise just speak to a West Bromwich Fan
Speed isn't a vector, it's scalar. Velocity is a vector (speed+direction). And acceleration has direction only indirectly.. you can accelerate by either speeding up (forwards) or slowing down (backwards), though which direction you are moving doesn't matter, you're either slowing up or you're slowing down. And who on Earth is West Bromwich... >_< Dan 00:08, 14 January 2006 (UTC)
replies: text: Speed is a scalar quantity, it only has magnitude. Velocity is a vector quantity it has a magnitude and direction, so it can be negative unlike speed. Rawsar6 (talk) 22:19, 21 January 2024 (UTC)
thread_title: speed 

message: I think it is useful to have a list of speed for common moving objects. Please join me if you agree. --Leo 14:59, 20 April 2006 (UTC)
thread_title: list of common speed 

message: A world class time for a marathon is less than 2.5 hours. That translates into about 16.8 km/hr or 10.5 miles /hr. While it would be wonderful if we all jogged at 10 miles / hr and could dream of hitting record paces if we trained a few extra hours everyday, these atheletes are slightly out of the league of the "average long distance jogger".
 dont believe anything i just edited this and no one even knows if any of this is true
I agree.  As an avid runner myself who enjoys running 10k or so every other day,  I never get those kinds of speeds.  I have a GPS watch which tells me my speed, and If im feeling good, I can keep up 13km/h for 30 minutes.  Then I come here and read the average speed is 16kph for long distance.  Theres no way that can be accurate.  I can see it being possible for the professional marathon runners,  but I myself, am already considered above average I think.  I would say an average run speed, based on my observations of other people, is around 9km per hour.007craft 16:31, 14 June 2006 (UTC)
replies: text: I would say 5-6 mi/h or about 8-10 km/h could be considered reasonably "average" for a long distance runner. For a concrete example, the median finishing time for the last New York marathon was about 4:39, which corresponds to a speed of 5.6 mi/h. Itub 16:11, 19 June 2006 (UTC)
thread_title:  Average Jogging Speed or World Class Marathoner? 

message: I'm sorry if this isn't the place, but has a page for "instantaneous speed" been created?  Or is there a page from which I can aquire information on it?  If not that might be a nice addition to this page as well.
het where is the speed and the egg color and the Icubation 
                     help kendra
           Can you give an example of what you would like to see on here?  what do you mean by instantaneous speed?  do you have any
reliable sources?  ~ORANGE~ 22:25, 28 March 2009 (UTC)
thread_title: Question

message: I have a question,
Why when you double the velocity of an object, you quadruple its speed rather than doubling it?
Has it anything to do with E=mc2 wherein mass is converted into energy by the square of light?
I mean if you "put" kinetic energy into an object, will part of it become "potential mass" and the rest actually become kinetic energy? Is that what explains why you have to square the number of times you want to increment the velocity in order to know the energy/power required?
I've looked everywhere and no one seems to explain why you have to square the energy in order to increment the velocity
I think you are a bit confused.  When you double the velocity, you do double the speed in the direction traveled.  All speed is, is the magnitude of the velocity.  Therefore both forward 3 m/s and backwards 3 m/s have the velocities +3 m/s and -3 m/s, respectively.  They have the same speed, 3.  What gets quadrupled is the kinetic energy.  KE = (1/2)mv^2 where m is mass and v is velocity.  If we plug in 2v for v (i.e. doubling velocity), we get the new kinetic energy (1/2)m(2v)^2 = (1/2)(m)(2^2)v^2 = 2mv^2.  We see this is quadrupled since 4*(1/2)mv^2 = 2mv^2.  As for the other part of the question about the role of E=mc^2.  This equation comes from special relativity and tells us how much energy an object would have if all mass could be converted to energy.   This formula is only useful with other energy equations when an object is moving at a substantial fraction (at least 10%) the speed of light and thus is not relevant to everyday calculations of velocity, speed, momentum, or energy.Aohara1986 06:42, 19 October 2007 (UTC)
thread_title:  4 times energy for doubled speed 

message: The article should use a consistent notation for speed; actually it´s difficult to read because of different symbols and the use of |v|. I think it could use v for velocity and v (in normal text) for speed, which  is common notation for vectors and scalars. --Canaima 01:14, 19 October 2007 (UTC)
thread_title:  Notation 

message: This article seems confusing on some accounts, and out right wrong on others. First of all, it defines speed as distance over time, but this is incorrect. Speed is the magnitude of instantaneous velocity. Secondly, it then goes on to discuss instantaneous speed in the portion of the article label "average speed".  —Preceding unsigned comment added by 128.230.85.11 (talk) 13:41, 4 September 2008 (UTC)
replies: text: Thank you for your suggestion. When you feel an article needs improvement, please feel free to make those changes.  Wikipedia is a wiki, so anyone can edit almost any article by simply following the  link at the top. The Wikipedia community encourages you to be bold in updating pages. Don't worry too much about making honest mistakes — they're likely to be found and corrected quickly. If you're not sure how editing works, check out how to edit a page, or use the sandbox to try out your editing skills.  New contributors are always welcome. You don't even need to log in (although there are many reasons why you might want to). --Closedmouth (talk) 13:58, 4 September 2008 (UTC)

text: I've made some changes to the article that hopefully make it less confusing (and not at all wrong!)  I've commented out the discussion of average speed, harmonic means and so on - not really a reflection on whether it was right or wrong, just that it seemed far too much detail for something that feels more like an introductory article.  If it's felt to be important, I would suggest putting it in a separate article with a link from this one.  Djr32 (talk) 18:59, 14 December 2008 (UTC)
thread_title:  confusing 

message: i have to do my science project and this is confuzing!  —Preceding unsigned comment added by 71.194.212.28 (talk) 11:26, 9 May 2009 (UTC)
thread_title:  huh? 

message: What is the fastest observed astronomical object? Albmont (talk) 17:28, 26 May 2009 (UTC)
thread_title:  Curious question 

message: I fail to see why the "length of path" (usually denoted by "s") is sometimes avoided or inapropriately substituted by "distance" or "displacement" in this article and elsewhere (e.g. in the article on work). If the statement
"The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval"
were true, then the average speed on a full circle would always be zero (zero displacement or distance between the initial and final point).  —Preceding unsigned comment added by 178.160.22.100 (talk) 00:58, 17 July 2010 (UTC)
replies: text: "Distance travelled" means something different to "distance between start and end". The first means path length, the second is a displacement. -- Dr Greg  talk  01:26, 17 July 2010 (UTC)
thread_title:  Length of path (s) cannot be substituted by "distance" 

message: Most of the derived SI units have been given eponymous names: Coulomb, Farad, Tesla and Watt are a few examples.
The only named unit of speed is the knot, which is not an SI unit. Defined as one nautical mile per hour, it is also imprecise, since the exact length of the nautical mile has varied over time and from one authority to another.
The SI unit of speed (actually velocity) is the metre per second, symbol: m·s-1. I propose that it should be given the name of Gonzales (symbol: Gz) after the eponymous "Speedy". The approved CGPM prefixes would apply very conveniently: a milli-Gonzales (mGz) would be appropriate for expressing things that move at a snail's pace, and the speed of light in a vacuum would be 299.792458 mega-Gonzales (MGz). I further propose that the micro-Gonzales (µGz) be treated as a special unit. It would be a dimensionless virtual unit, reserved for expressing the speed at which committees move towards a final decision.
martinev (talk) 13:14, 12 October 2010 (UTC)
replies: text: Try asking the BIPM to do that, or even try to popularize this unit yourself.  Anyway, article talk pages on Wikipedia are for discussing improvement to the associated article. A. di M. (talk) 18:47, 12 October 2010 (UTC)
thread_title:  Gonzales unit 

message: The article on speed is nice little article, with neat mathematical presentation. Still, it could be somewhat improved, particularly with respect to constant and average speed. Also, the use of the expression "distance travelled" (especially when without "travelled") may be misleading, the "length of the path travelled" would be better. But the main problem is that speed is explained (particularly in the lead) using a more complex notion of velocity.
This should be avoided in the lead, or the two articles should be merged. The velocity article is a mess anyway, and it should be written anew. The only issue is whether speed should be kept as a separate article. Any suggestions?--Ilevanat (talk) 00:41, 16 December 2011 (UTC)
thread_title:  Speed and velocity 

message: The usage and primary topic of  is under discussion, see Talk:Slowness (novel) -- 70.51.44.60 (talk) 22:54, 1 December 2015 (UTC)
thread_title: "Slowness"

message: Most of the article's current text is unsourced, making it difficult or impossible to check the claims and expand the article. It is better to avoid popular physics books for laypeople, except for the more introductory passages. Always give preference, whenever possible, to peer-reviewed, rigorous and formal, scrutinized academic studies on physics, which require more background on mathematics and physics to be understood but provide much more guidance on where to find more information about the uses and limitations of this concept. --A concerned user: Hayohamm (talk) 05:35, 20 July 2016 (UTC)
thread_title:  Citations are needed 

message: some letters also not displayed Kalpras (talk) 20:46, 21 April 2022 (UTC)
thread_title:  equations not displayed, Why? 

message: So it should be linked to this article's section Average speed (e.g.: "see also: ..."). I can not do it because this article is protected. 212.178.135.35 (talk) 14:05, 3 January 2023 (UTC)
thread_title:  Article [[Harmonic mean#Average speed|Harmonic mean, section Average speed]] has some additional info about computing average speed. 

message: I think this is not accurate. If in one dimension point A is 1 meter away from point B at time 0 and its speed is 6 m/s for all time, the antiderivative of speed is 6t + c. The c is 1, but for the expression to be the distance travelled c would have to be equal 0. Body A did not travel that first meter, it was already one meter away. In fact, the constant of integration would always have to be 0, which is not the case. 2.36.100.158 (talk) 20:46, 5 April 2024 (UTC)
replies: text: No, you are wrong. "f is the derivative of g" does not imply "g is the only antiderivative of f".  (6 m/s)t is an antiderivative of 6 m/s and thus it is correct that 6 m/s is the derivative of (6 m/s)t. It's also the derivative of (6 m/s)t + 3 m; that doesn't mean it's suddenly not the derivative of (6 m/s)t anymore. There's nothing wrong with that. For clarity, a constant of integration is not part of an antiderivative, but rather provides a convenient way to denote the set of all antiderivatives.--Jasper Deng (talk) 21:01, 5 April 2024 (UTC)
replies: text: Right, thank you for this 2.36.106.75 (talk) 18:08, 13 April 2024 (UTC)
thread_title:  If s is the length of the path (also known as the distance) travelled until time t, the speed equals the time derivative of s