# Do larger things fall faster?

**URL:** <https://boards.straightdope.com/t/do-larger-things-fall-faster/854154>\
**Category:** Factual Questions\
**Created:** [May 19, 2020, 11:53pm UTC](https://boards.straightdope.com/t/do-larger-things-fall-faster/854154 "2020-05-19T23:53:37Z")\
**Posts on this page:** 5\
**Page:** 2

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**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\
**Post date:** [May 22, 2020, 11:38am UTC](https://boards.straightdope.com/t/do-larger-things-fall-faster/854154/21 "2020-05-22T11:38:58Z")

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> [@md2000](#):
>
> The key number here is terminal velocity … For humans, this is typically about (rumor has it) 100mph.

More like 120, for the standard belly-to-earth stable position.

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**Author:** ![Corry\_El](https://avatars.discourse-cdn.com/v4/letter/c/ecae2f/32.png) [@Corry\_El](https://boards.straightdope.com/u/Corry_El)\
**Post date:** [May 22, 2020, 2:05pm UTC](https://boards.straightdope.com/t/do-larger-things-fall-faster/854154/22 "2020-05-22T14:05:02Z")

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> [@Reply](#):
>
> Doesn’t have to do with the kinetic energy of the shell? It takes a lot more to move or stop it.
> 
> Think a 9mm has like 500 joules. A battleship shell, maybe 300,000,000?

Assuming they have the same velocity (which is close enough to make a rough point in case of say M4 carbine firing 5.56mm bullet, relatively slightly higher muzzle velocity than a modern long barreled 155m gun-howitzer at full charge; a 9mm round fired from a pistol has much lower muzzle velocity than a 16"/50 AP shell with full propelling charge), the energy is in the ratio of mass, ~m\*(v^2)/2, so back to my example the 155mm shell has around 21,700 times as much energy, or momentum (m\*v) as the rifle bullet.

However air resistance is acting on a cross section only ~777 times larger in case of the 155mm shell than 5.56mm bullet, and air resistance is approximately proportional to that area. That’s assuming same drag coefficient because same shape, which is not quite correct because of scale effect on flow regime (different Reynolds number), but it’s practically close. A bigger error is assuming air density is the same. Actually you’d fire the 155mm at greater than theoretical 45deg elevation for max range (in a vacuum) because of the benefit of getting the shell to thinner air sooner in its flight. You’d fire the rifle at \<45 deg elevation to get max range because even at 45 deg you waste too much energy overcoming air resistance.

Anyway the _biggest_ effect between those two is the bullet’s much higher air resistance (in a given density of air at a given velocity) relative to its mass. The air decelerates it according to F=ma. ‘F’, the force of air resistance, is much bigger relative to ‘m’ for a rifle bullet than an artillery shell.

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**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\
**Post date:** [May 22, 2020, 7:58pm UTC](https://boards.straightdope.com/t/do-larger-things-fall-faster/854154/23 "2020-05-22T19:58:27Z")

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> [@Hampshire](#):
>
> [video](https://www.youtube.com/watch?v=E43-CfukEgs)
> 
> Similar experiment at NASAs massive vacuum chamber with a bowling ball and feathers.

Loki’s arrival on Earth in _The Avengers_ was filmed in that same chamber: [https://www.youtube.com/watch?v=pQKYN-yR2oM](https://www.youtube.com/watch?v=pQKYN-yR2oM)

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**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\
**Post date:** [May 24, 2020, 1:00am UTC](https://boards.straightdope.com/t/do-larger-things-fall-faster/854154/24 "2020-05-24T01:00:55Z")

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Rosenkrantz et al [already proved it](https://www.youtube.com/watch?v=maI53H4Zbrs).

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**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\
**Post date:** [May 24, 2020, 2:40pm UTC](https://boards.straightdope.com/t/do-larger-things-fall-faster/854154/25 "2020-05-24T14:40:31Z")

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> [@TriPolar](#):
>
> Don’t worry about it, it means Never Mind.

Ah. Now i know.  
Cheers.

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