# Does weight matter for the speed of a falling object in an atmosphere? **URL:** \ **Category:** Factual Questions\ **Created:** [December 3, 2010, 8:55pm UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858 "2010-12-03T20:55:34Z")\ **Posts on this page:** 17\ **Page:** 2
**Author:** ![ClaytonThroop](https://avatars.discourse-cdn.com/v4/letter/c/e99b99/32.png) [@ClaytonThroop](https://boards.straightdope.com/u/ClaytonThroop)\ **Post date:** [December 3, 2010, 11:14pm UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/21 "2010-12-03T23:14:33Z")
For whatever it’s worth - it’s common in skydiving for lighter jumpers to wear weight belts when jumping with heavier jumpers. Fall rate can be changed by altering body position, to an extent, but not always enough to overcome the weight difference for a given activity with a given person (also depending on the skill level of the participants). ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [December 3, 2010, 11:17pm UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/22 "2010-12-03T23:17:05Z")
> [@spenczar](#): > > And my point is that “most important” is not well defined. The difference you are talking about in shape is enormous. That lead sphere is about a foot in diameter, the javelin is maybe half an inch. A 1kg ball of lead is going to fall a lot faster than a 40g sphere made out of balsa wood, no? And MY point is that when you change the shape but leave the weight the same, the speed of the falling object change. The reverse is not true. Of course, as you correctly pointed out upthread, changing the weight but not the shape calls the speed of falling to change as well. To me this indicates that weight is not the single prime determinant of the speed of a falling object. ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [December 3, 2010, 11:18pm UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/23 "2010-12-03T23:18:13Z")
> [@Snarky\_Kong](#): > > Isn’t a sphere the same as a javelin to a topologist? So long as there is no hole in the javelin, I will agree without qualification. ---
**Author:** ![Snarky\_Kong](https://avatars.discourse-cdn.com/v4/letter/s/a183cd/32.png) [@Snarky\_Kong](https://boards.straightdope.com/u/Snarky_Kong)\ **Post date:** [December 3, 2010, 11:21pm UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/24 "2010-12-03T23:21:29Z")
> [@Skald\_the\_Rhymer](#): > > To me this indicates that weight is not the single prime determinant of the speed of a falling object. I don’t think anybody, at least on this board, has made that claim. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 3, 2010, 11:28pm UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/25 "2010-12-03T23:28:17Z")
> [@](#): > > And MY point is that when you change the shape but leave the weight the same, the speed of the falling object change. The reverse is not true. If I’m parsing that correctly, the reverse _is_ true: If you change the weight but leave the shape the same, the speed will also change. ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [December 3, 2010, 11:32pm UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/26 "2010-12-03T23:32:31Z")
> [@Chronos](#): > > If I’m parsing that correctly, the reverse _is_ true: If you change the weight but leave the shape the same, the speed will also change. It’s not so much that you parsed it incorrectly as that I phrased it very, very badly. 🙂 Since you can change the shape in multiple ways while leaving the weight the same, and doing so will cause the speed of at which an object falls to change, it seems clear that weight is not _the_ determinant of how fast an object falls. No? ---
**Author:** ![spenczar](https://avatars.discourse-cdn.com/v4/letter/s/858c86/32.png) [@spenczar](https://boards.straightdope.com/u/spenczar)\ **Post date:** [December 3, 2010, 11:41pm UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/27 "2010-12-03T23:41:52Z")
> [@Skald\_the\_Rhymer](#): > > To me this indicates that weight is not the single prime determinant of the speed of a falling object. _There is no single prime determinant_. That phrase doesn’t even really have any meaning. For a bacterium or a yeast cell, the terminal velocity is almost 100% determined by weight. For a space shuttle, the terminal velocity has nearly zero dependence on weight. Everyone agrees there are multiple factors. The relative importance of those factors very, very strongly depends on their magnitudes. ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [December 3, 2010, 11:46pm UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/28 "2010-12-03T23:46:58Z")
> [@spenczar](#): > > _There is no single prime determinant_. That phrase doesn’t even really have any meaning. For a bacterium or a yeast cell, the terminal velocity is almost 100% determined by weight. For a space shuttle, the terminal velocity has nearly zero dependence on weight. > > Everyone agrees there are multiple factors. The relative importance of those factors very, very strongly depends on their magnitudes. Okay, we’re arguing past each other. My point in the thread that birthed this one was that, to the casual eye, it can easily seem that weight IS the prime determinant of the speed of a falling body in atmosphere. I agree that it is not, and clearly you do too. I don’t think I’ve argued that shape, size, or density, is the prime determinant, but it’s possible that I did so; if I did, that was an error on my part: neither what I understand the case to be to, nor what I intended to state. I was making an analogy between Pascal’s Wager (superficially convincing, but filled with errors if you look closely because it does not take note of the complexity of the subject) and the common-sensical notion that heavy objects always fall faster than lighter ones. ---
**Author:** ![spenczar](https://avatars.discourse-cdn.com/v4/letter/s/858c86/32.png) [@spenczar](https://boards.straightdope.com/u/spenczar)\ **Post date:** [December 4, 2010, 12:09am UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/29 "2010-12-04T00:09:24Z")
> [@Skald\_the\_Rhymer](#): > > Okay, we’re arguing past each other. > > My point in the thread that birthed this one was that, to the casual eye, it can easily seem that weight IS the prime determinant of the speed of a falling body in atmosphere. I agree that it is not, and clearly you do too. I don’t think I’ve argued that shape, size, or density, is the prime determinant, but it’s possible that I did so; if I did, that was an error on my part: neither what I understand the case to be to, nor what I intended to state. I was making an analogy between Pascal’s Wager (superficially convincing, but filled with errors if you look closely because it does not take note of the complexity of the subject) and the common-sensical notion that heavy objects always fall faster than lighter ones. Totally fair, I’m sorry I misunderstood your point. I have no idea what was discussed in the Pascal’s Wager thread, and was only responding to arguments made in this thread, which may have been a bit silly, but GD threads are just always so damn messy. I hate wading through them. ---
**Author:** ![Topologist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/topologist/32/3208_2.png) [@Topologist](https://boards.straightdope.com/u/Topologist)\ **Post date:** [December 4, 2010, 1:22am UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/30 "2010-12-04T01:22:21Z")
> [@Skald\_the\_Rhymer](#): > > Is there a topologist in the house? Yes, sorry I’m late to the party. > [@Skald\_the\_Rhymer](#): > > Topologist was more amusing than geometer. Thank you. But if you actually want to _measure_ differences in shape it’s a geometer you want. > [@Snarky\_Kong](#): > > Isn’t a sphere the same as a javelin to a topologist? Yes, which may be why I’m not much good in the decathlon. I don’t actually have much to add to what’s been said, but there were so many straight lines… ---
**Author:** ![Indistinguishable](https://avatars.discourse-cdn.com/v4/letter/i/90ced4/32.png) [@Indistinguishable](https://boards.straightdope.com/u/Indistinguishable)\ **Post date:** [December 4, 2010, 3:04am UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/31 "2010-12-04T03:04:30Z")
> [@Topologist](#): > > Thank you. But if you actually want to _measure_ differences in shape it’s a geometer you want. Hm… > [@](#): > > I don’t actually have much to add to what’s been said, but there were so many straight lines… Impostor! How could you tell they were straight?! ---
**Author:** ![Topologist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/topologist/32/3208_2.png) [@Topologist](https://boards.straightdope.com/u/Topologist)\ **Post date:** [December 4, 2010, 3:17am UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/32 "2010-12-04T03:17:21Z")
> [@Indistinguishable](#): > > Impostor! How could you tell they were straight?! Well, I could tell they were lines. It didn’t actually matter to me whether they were straight or not. ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [December 4, 2010, 3:49am UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/33 "2010-12-04T03:49:36Z")
> [@Snarky\_Kong](#): > > The drag force is not dependent on mass, so mass/weight cannot cancel out and the acceleration of a falling object is dependent on weight. Anyone hear of someone named Gallileo? The acceleration of a falling object is a constant: 32 ft/sec^2 That applies to both a feather and a lead weight. Drag will slow acceleration, but any two objects accelerate at the same rate in the same gravitational field. At a certain point, an object will reach a terminal velocity, but that has nothing to do with acceleration. ---
**Author:** ![spenczar](https://avatars.discourse-cdn.com/v4/letter/s/858c86/32.png) [@spenczar](https://boards.straightdope.com/u/spenczar)\ **Post date:** [December 4, 2010, 4:02am UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/34 "2010-12-04T04:02:48Z")
> [@RealityChuck](#): > > Anyone hear of someone named Gallileo? > > The acceleration of a falling object is a constant: 32 ft/sec^2 That applies to both a feather and a lead weight. No, the gravitational force is a constant, but the total acceleration isn’t, because drag (which has units of force) is not a constant. The total acceleration is (gravitational force - drag) / mass, and drag depends on shape, velocity, and the local air conditions. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 4, 2010, 4:53am UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/35 "2010-12-04T04:53:55Z")
Quoth **spenczar** : > [@](#): > > There is no single prime determinant. That phrase doesn’t even really have any meaning. For a bacterium or a yeast cell, the terminal velocity is almost 100% determined by weight. For a space shuttle, the terminal velocity has nearly zero dependence on weight. I’m not sure what you mean by this. Terminal velocity has the same dependence on mass for all objects. If you quadruple the mass of a bacterium, its terminal velocity will double. If you quadruple the mass of the Space Shuttle, its terminal velocity would also double. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [December 4, 2010, 11:56am UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/36 "2010-12-04T11:56:30Z")
> [@RealityChuck](#): > > Anyone hear of someone named Gallileo? > > The acceleration of a falling object is a constant: 32 ft/sec^2 That applies to both a feather and a lead weight. Only in a vacuum. Galileo was idealizing to the case of objects falling in a vacuum. In a sense, Galileo’s real discovery was the realization that falling in a vacuum should be treated as the paradigmatic case of falling, as opposed to Aristotle, who regarded falling through a medium as the paradigmatic case, and thus concluded (quite rightly, as far as it goes) that speed of fall depends on weight and the density of the medium. At a purely empirical level, Aristotle was right (although he extrapolated to some false conclusions, such as that speed of fall in a vacuum would be infinite), which is why it is a myth that Galileo refuted Aristotle’s view _experimentally_ (he did not, and he did not claim to have done so). However, Galileo’s idealization provides a much greater insight into the true underlying mechanical principles. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [December 6, 2010, 12:38pm UTC](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858/37 "2010-12-06T12:38:36Z")
> [@Skald\_the\_Rhymer](#): > > At any rate, it’s not the weight that determines the speed of falling. Basically \*\*Skald \*\*old fellow your analogy in that other thread was a complete dud. I could see the point you were making but the problem is that believing “that the speed an object falls at is dependent on its weight” is absolutely and utterly correct for most human experience and you didn’t specify a set of conditions under which that belief would be invalid. For most human experience the speed an object falls is dependent on weight due to its effect in overcoming drag. Also, you you didn’t insert the qualification “primarily” before the word “dependent” as you are now doing. The SDMB being what it is you then got deservedly hijacked 😉 [Previous page](https://boards.straightdope.com/t/does-weight-matter-for-the-speed-of-a-falling-object-in-an-atmosphere/562858.md?page=1)