Talk:Free fall

message: The first fgiklghi line says: "Free fall is motion with no acceleration other than that provided by gravity, and no deceleration other than that caused by the aerodynamic drag of the object". Then a few lines down it says:
"Examples of objects not in free fall: ... Jumping from an airplane"
What!? ExitLeft (talk) 00:46, 7 December 2007 (UTC)
thread_title: A contradiction in the article!

message: An anon just ammended the reference to Vesna Vulovic, in what was probably a well meaning attempt to avoid nationallistic bias . However, I suspect the plane didn't blow up over both the Czech Republic and Slovak Republic. Does anyone know the more precise location based on today's boundaries? -- Solipsist 21:51, 11 Jun 2005 (UTC)
replies: text: Here: Srbska Kamenice. Article updated. Pavel Vozenilek 22:02, 11 Jun 2005 (UTC)
thread_title: Czechoslovakia 

message: The mentioned accident was not a good example in this case. I read on http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=1973796 that she opened her reserve parachute, however it failed to inflate properly. Such accidents (hard landings because of parachute malfunction) happen from time to time in skydiving and this particular one was not something very unique or at least not as unique as the Yugoslavian girl that survived plane crash. Shayna had partially inflated parachute what reduced her terminal velocity and thus it was not a pure free fall. I suggest removing this part from this article.
:The video makes it clear she wasn't in freefall, so I removed the reference. Rklawton 20:51, 11 February 2006 (UTC)
thread_title:  Shayna Richardson Accident 

message: I was going to add a See also to Tiny Broadwick, an article I just started, based on Googling up some research... Actually, that article could use some expansion, so if anyone is interested, please make some changes. -HiFiGuy 19:39, 1 March 2006 (UTC)
thread_title:  Tiny Broadwick 

message: The equation is derived from the assumption that the acceleration is dependent on mass and gravity (m * g) whereas in reality in only depends on gravity (g). Secondly, there is a problem with the latex implementation. I'd rather someone with a better math/physics background fix the equation before I attempt to myself. --216.170.141.157 22:51, 25 May 2006 (UTC)
replies: text: I've moved this comment to the bottom, because Wikipedia convention is to add new comments to the bottom of the page.  Now, I was under the impression that free-fall under constant gravity without drag is only dependent on gravity, but free-fall with drag is dependent on the shape, size, and mass of the object as well, which is why a lead ball falls faster than a feather.  I can't confirm the correctness of the equation, but I can say that acceleration with drag is NOT dependent only on gravity. TomTheHand 23:31, 25 May 2006 (UTC)

text: Righto, but remember, we're mixing apples and oranges.  That is, there are two different definitions of freefall in play here.  One relates to skydiving and the other relates to physics.  Let's just make sure the article is clear on the difference - and keeps them separate.  Rklawton 06:24, 26 May 2006 (UTC)
thread_title: Problem with the drag equation

message: I would say 'freefalling' in the parachutist sense is not freefall.  It is 'dropping' or 'falling'.  It doesn't hurt until you land :).  Plenty of air-resistance acting on you.  Whereas freefall would when there is no net force acting on you.  ie: when forces are balanced (ie: zero-g, gravity is countered by your orbital speed).  If you were outside the Sun's gravity well, you might be effectively in free-fall...  I guess nowhere are you outside of the reach of gravity. But the lack of sensation of forces pulling on your mass == freefall.-- ~ender 2005-03-13 12:00:MST
#Note that zero-g is independent of gravity.  A mass is in zero-g when no force other than gravity is acting on that mass.  You, the reader are presently prevented from experiencing zero-g for significant periods because your chair is firmly pushing on your butt.  Jumping up will temporarily place you in zero-g – until you hit something.  Rklawton 22:52, 3 June 2006 (UTC)
thread_title: Freefalling and parachutists

message: I have found multiple sources saying different speeds at which Kittinger fell.  This USAF site says it was 714 mph and this Time magazine article says it was 614 mph.  I assume one is a typo since they're only off by one digit.  Which would people suggest we use?  This obviously has implications in many other articles too. 
--W00tfest99 19:02, 19 February 2007 (UTC)
replies: text: I'm confused (a familar sensation for me).  If the terminal velocity for a human body is approximately 124mph, how did Kittinger reach 614mph?  Was he using some form of external propulsion (which wouldn't be a 'free fall' in my mind)?  Or is it because he was falling in a rocking-chair position, which offers less drag than an arms-and-legs-outstreached, stomach-down position?Tesseract501 (talk) 19:06, 9 February 2013 (UTC)
thread_title:  Record free fall speed 

message: I'm probably just thick, but when you are in free fall, accelerating under only the influence of gravity, you feel weightless (zero G). 
On the other hand, when your acceleration is caused by any force other than gravity, you feel a sense of weight (G forces).  
This keeps me awake at night.  
What gives?
125.161.130.92 (talk) 21:51, 17 November 2007 (UTC)
thread_title:  Acceleration Due to Gravity Versus Acceleration Due to Other Forces 

message: The article says that jumping from an airplane is not a free fall. Several paragraphs below the cases of people jumping from the planes are given as examples of free falls. Can you make it somehow... more clear...  —Preceding unsigned comment added by 95.58.136.113 (talk) 14:39, 7 April 2009 (UTC)
thread_title:  LOL didn't get it! 

message: The section 'Free-fall in Newtonian mechanics' should be 'Free fall in scholastic mechanics', according to which gravitational fall was a uniformly accelerated motion because they thought gravity was a constant, as did Galileo in his scholastic mechanics and radically mistaken law of free-fall, whereas in Newtonian mechanics gravitational fall is increasingly exponentially accelerated. See Proposition 32 of Book 1 of Newton’s Principia for his distance-times law for gravitational free-fall.
I flag the title for clarification.
--Logicus (talk) 18:18, 23 July 2009 (UTC)
thread_title: Free-fall in scholastic mechanics error

message: The "Surviving falls" section anecdotes all need to specifically say whether the person actually free-fell to the ground.  Currently they are all maddeningly vague about this point:  Was each of them strapped into an aircraft seat as he/she free-fell?  Or was it more of a skydiving free-fall?  Tempshill (talk) 07:42, 27 November 2009 (UTC)
thread_title:  "Surviving falls" anecdotes each need to specifically say free fall 

message: Where does this Physics definition come from: "Free fall describes any motion of a body where gravity is the only or dominant force acting upon it, at least initially. Since this definition does not specify velocity..."?
Halliday & Resnick; Fundamentals of Physics, 3rd Ed states "Free fall means falling in a vacuum, so that the frictional resistance and buoyant effect of the air do not affect the motion." p21
The significant difference here is that the definition Halliday & Resnick define "free fall" as actually involving falling.  Who defines it in such a way as to not involve falling?
In common sense terms, the name "free fall" would suggest that it is a subset of falling.  —Preceding unsigned comment added by 96.52.231.179 (talk) 01:56, 28 February 2010 (UTC)
thread_title: Physics definition

message: Norbeck who has contributed to section Inverse square law gravitational field has answered my question on free fall time.The question was What is the free fall time from Earth orbital radius (~150 million km.) to Sun. The answer can readily be found by numerical methods. But using Norbeck's equation it is much simpler. It is 64.56 days and it is related to the period of revolution around the Sun. I found   \mathbf {t} = \sqrt{\frac{1}{32}} \cdot T 
where t is the free fall time and T is the period of revolution. 
(Sbharris also contributed to discussion by pointing out that the same relation can be found by using semi major axis of infinite eccentricty ellipse instead of radius in Kepler's third law. ) Nedim Ardoğa (talk) 11:24, 10 March 2010 (UTC)
replies: text: safeer Khan 37.111.168.65 (talk) 16:31, 29 May 2024 (UTC)
thread_title:  Free fall time 

message: Equations for a falling body and this article (Free fall) are basically the same thing.sanpaz (talk) 21:57, 9 April 2010 (UTC)
replies: text: I just found another article about the same thing...Falling (physics).sanpaz (talk) 22:08, 9 April 2010 (UTC)
replies: text: I'm fine with the merge... I'd leave the main page at Free fall and redirect the rest. Qfl247 (talk) 22:43, 24 May 2010 (UTC)
replies: text:  Agreed. I don't see much unique to Falling (physics). I'm just going to nuke it now. If you liked anything there, feel free to recover it to this page. —Ben FrantzDale (talk) 12:49, 9 June 2010 (UTC)
thread_title:  Merger proposal 

message: --Guerinsylvie (talk) 14:34, 18 August 2010 (UTC)
thread_title:  paragraph 2.3 needs a modification ? 

message: Could someone with access to the article Buckman 1991 (PMID 2003254) in the journal The Surgical clinics of North America - or will to search for any other potential source - check if there is any specific height given that causes mortality in 50% in cases for adults - or any other equivalent measure of fatal height? 
The thing is, according to Mosenthal 1995 (PMID 7760404) "The 50% mortality for free falls in children occurs at five to six stories (60 to 72 feet), while for adults it occurs at four stories (48 feet)". However, it cites, in turn, Buckman 1991 as well as Barlow 1983 (PMID 6620098). However, when looking into Barlow 1983, it actually states "between 5th and 6th floors", which, assuming US convention, corresponds to between 4 and 5 storeys above the ground, which would rather correspond to something like 40 to 50 feet. It doesn't give what is the case for adults, so I assume Mosenthal got it from Buckman. However, I don't have access to that original article by Buckman myself, but it should still be checked to see what Mosenthal really meant. Mikael Häggström (talk) 14:20, 2 January 2011 (UTC)
thread_title:  What is fatal height for adults? 

message: In the Record Free Fall section, it says Eugene Andreev jumped from 83,523 in 1962.  Though "later" jumpers would ascend higher.
Then talking about Captain Kittinger, it says his record jump at 102,800 feet occured in 1960.
Either the word later should be "other" or the dates are wrong. You can't jump later and have it be in the past :-)  — Preceding unsigned comment added by 207.171.191.60 (talk) 01:49, 10 July 2012 (UTC)
thread_title:  Record Free fall section has an error 

message: I don't see an explanation anywhere of why extremely-high-altitude jumpers reach a higher velocity than regular jumpers (at least in the non-mathematical sections). (Would they slow down to the regular terminal velocity after hitting regular-jump height?) This makes the following paragraph confusing:
"Another factor to mention is that a falling person will reach terminal velocity after some 12 seconds or so, falling some 450 m (about 1,500 ft) in that time. That person will not then fall any faster, so it makes no difference what distance they fall if it is more than 1,500 ft - they will still reach the ground at the same speed."
Genepoz (talk) 23:19, 8 October 2012 (UTC)
thread_title:  Contradiction (or simply unclear) about terminal velocity in "Surviving Falls" section 

message: I think this section needs to be rewritten. It says that no one tested Aristotle's ideas but on the page for John Philoponus, who lived a millenium earlier, it quotes him as having carried out the test. I'd prefer if someone who's more familiar with editing Wikipedia asnd who knows how to create a link would correct this rather than attempting it myself.  — Preceding unsigned comment added by Jjc2002 (talk • contribs) 14:07, 5 February 2014 (UTC)
thread_title:  History  

message: The usage and primary topic of 
 is under discussion, see talk:Fall (disambiguation) -- 70.51.202.113 (talk) 04:04, 2 September 2015 (UTC)
thread_title: "Fall"

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thread_title:  External links modified 

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thread_title:  External links modified (January 2018) 

message: IMO, the concept of free fall in physics should not be mixed up with arbitrary material on skydiving and plane crash survivors. I've moved the skydiving section to Parachuting, copied the survivor section into Falling (accident) and will remove the latter here once it's no longer linked on the main page. Any objections? OnceAndFutureFlopsy (talk) 21:45, 28 August 2019 (UTC)
thread_title:  Removing off-topic sections 

message: At the moment I come across a warning This article possibly contains original research.'
I find it very hard to find any research in the affected paragraph - let alone original research. Most of the stuff is as old as - ok not Metusalah - but Galileo ? So ... may we laugh ? Sjoerd22 (talk) 15:49, 2 July 2022 (UTC)
thread_title:  Original?