# Coriolis effect and location inside a spinning object **URL:** \ **Category:** Factual Questions\ **Created:** [February 3, 2025, 12:05am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792 "2025-02-03T00:05:16Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 3, 2025, 12:05am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/1 "2025-02-03T00:05:16Z")
In several of the Expanse books, the authors contend that the Coriolis effect is greater closer to the axis. For example in Nemesis Game: > Bistro Rzhavchina was _high up toward_ the center of spin. > Coriolis here started to have an effect just north of subliminal, and that wasn’t a thing that Earthers and Martians ever became really comfortable with. But the Coriolis effect has nothing to do with distance from the axis, right? It’s just related to the rate of spin, the velocity of motion being affected, and the angle between the spin axis and the velocity. Am I missing something - or are the authors missing something? ---
**Author:** ![ParallelLines](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/parallellines/32/3575_2.png) [@ParallelLines](https://boards.straightdope.com/u/ParallelLines)\ **Post date:** [February 3, 2025, 12:28am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/2 "2025-02-03T00:28:02Z")
I haven’t read those novels, and I’m not sure how they’re using Coriolis effect as a descriptor on such a small (comparative to a planetary) scale. They MAY be talking about the effect higher speed rotations have on many people and the resulting issue of using small radius high speed rotation for simulating gravity. An article: > **[The Problem With Spinning Spacecraft](https://www.wired.com/story/the-problem-with-spinning-spacecraft/)** > > To send astronauts on long-term space missions, it’ll take rotating habitats to produce artificial gravity. But that’s trickier than you might think. > Since the person is in a rotating vehicle, both their head and their feet have the same angular velocity (ω). However, they are not moving in a circle of the same size. The head is closer to the center of the rotating craft than the feet, so that the circular path radius of the head (Rh) is smaller than that for the feet (Rf). Remember that the value of the acceleration (and thus the artificial gravity) decreases with the radius of motion. The person’s head will experience a smaller gravitational field than their feet. That’s a little weird. The above quote being a possible example of a situation where part of the body being closer to the center/axis causing disruption. I’ll await more quotes to establish context, another reader of the series to give their $0.02, or someone like @Stranger_On_A_Train who’s talked at length (and great detail/accuracy) in other threads on long-duration space travel with current or near future tech. [for the records, I’m not super-well studied on these sciences, but had read about the above issue in regards to other semi-hard sci-fi novels that talked about gravity simulation where the rotational issue I mentioned above was discussed. The answer for that and the speed of rotation issue in the also covered in the article was a VERY big (for spaceships) ring rotating much more slowly] ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 3, 2025, 12:35am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/3 "2025-02-03T00:35:23Z")
For context the Bistro is in > **[10 Hygiea](https://en.m.wikipedia.org/wiki/10_Hygiea)** > > 10 Hygiea is a major asteroid located in the main asteroid belt. With a mean diameter of between 425 and 440 km and a mass estimated to be 3% of the total mass of the belt, it is the fourth-largest asteroid in the Solar System by both volume and mass, and is the largest of the C-type asteroids (dark asteroids with a carbonaceous surface) in classifications that use G type for 1 Ceres. It is very close to spherical, apparently because it had re-accreted after the disruptive impact that produce ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [February 3, 2025, 12:41am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/4 "2025-02-03T00:41:14Z")
The [Wikipedia article](https://en.wikipedia.org/wiki/Coriolis_force) agrees that the force is greatest near the poles: > The horizontal deflection effect is greater near the [poles](https://en.wikipedia.org/wiki/Geographical_pole), since the effective rotation rate about a local vertical axis is largest there, and decreases to zero at the [equator](https://en.wikipedia.org/wiki/Equator). and later > The acceleration affecting the motion of air “sliding” over the Earth’s surface is the horizontal component of the Coriolis term > -2\,{\boldsymbol {\omega }}\times \mathbf {v} > This component is orthogonal to the velocity over the Earth surface and is given by the expression > \omega \,v\ 2\,\sin \phi > where > \omega is the spin rate of the Earth > \phi is the latitude, positive in the [northern hemisphere](https://en.wikipedia.org/wiki/Northern_hemisphere) and negative in the southern hemisphere ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [February 3, 2025, 1:03am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/5 "2025-02-03T01:03:18Z")
Just to give context, the effect @ParallelLines described is exactly what the _Expanse_ authors were talking about. The differing speeds of the head versus feet would result in nausea for people not used to it. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 3, 2025, 1:07am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/6 "2025-02-03T01:07:15Z")
Ah, but that’s for the Earth - because near the poles _the direction_ of wind velocity is nearly perpendicular to the rotation axis. _Inside_ an asteroid, there’s no such factor (I think) ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [February 3, 2025, 1:22am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/7 "2025-02-03T01:22:41Z")
Perhaps that’s badly said, or perhaps there’s underlying confusion. The forces have nothing to do with any atmosphere. They palpably _affect_ an atmosphere, but that’s because atmospheres are soft and squishy and portable. The forces exist even in a vacuum. In fact they exist throughout the solid rock of a solid rigidly rotating body. The issue is that Coriolis forces on asteroid-sized bodies rotating slowly are not all that strong. Not enough to stress the rock appreciably. So you would not notice them by any effect they might have on that rock. OTOH, if the asteroid was a hollow gas-filled shell, the forces would most certainly affect the interior atmosphere. And the faster it spins the more that’s true. Also the closer to the poles one is situated. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 3, 2025, 1:46am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/8 "2025-02-03T01:46:50Z")
The more basic equation in that article is > Coriolis force, −2𝑚(𝜔×𝑣′) which doesn’t include distance, so the force would be identically large inside near the center or inside near the surface ---
**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:** [February 3, 2025, 1:50am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/9 "2025-02-03T01:50:36Z")
Is this asteroid spinning as a single rigid body, or are different height-layers of it spinning at different speeds so as to produce the same gravity in each one? ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 3, 2025, 1:54am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/10 "2025-02-03T01:54:02Z")
I believe it’s spinning as a rigid body ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [February 3, 2025, 2:07am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/11 "2025-02-03T02:07:50Z")
> [@Andy\_L](#): > > which doesn’t include distance, so the force would be identically large inside near the center or inside near the surface Yes, but the effective gravity differs with radius. So at the inner levels, the Coriolis force is larger compared to gravity. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 3, 2025, 2:16am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/12 "2025-02-03T02:16:53Z")
That’s true Is it reasonable to think that people can sense the ratio of centrifugal to Coriolis force? ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [February 3, 2025, 2:18am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/13 "2025-02-03T02:18:55Z")
Probably not. But they can readily sense that the total force they feel is a) not consistent from head to foot, and b) not aligned at 90 degrees to the floor they’re standing on. Those things would really stand out to somebody raised on a real planet or sufficiently large rotating space Ark. The fact their sense of the forces would change whether they’re walking north, south, east, or west would really limit their ability to adapt to a “new normal”. Since “normal” would not be consistent over even short periods of time. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 3, 2025, 2:21am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/14 "2025-02-03T02:21:26Z")
That’s more the centrifugal force that’s inconsistent between head and feet - but I can believe that _characters_ might confuse the too ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [February 3, 2025, 2:55am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/15 "2025-02-03T02:55:06Z")
Coriolis force requires that you are moving (at least in part) in a direction normal to the axis of rotation. If you are still, there is no Coriolis force. It isn’t a measure of differences in centrifugal force. This is why there is a velocity component to the formula. More importantly this velocity is only your velocity relative to the axis of rotation. So on a sphere the velocity component of your motion relative to the axis of rotation changes with the sine of your latitude. It is zero at the equator and maximum at the poles. Someone walking near the pole of a fast rotating sphere would feel a pull to the side when walking north or south diminishing to nothing walking east or west. At the equator they would feel no such force, but the Eötvös effect may become noticeable for east and west motion. If you had a long enough drop at the equator a dropped object would be subject to Coriolis force, because it is moving normal to the axis if rotation. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 3, 2025, 11:07am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/16 "2025-02-03T11:07:00Z")
Thanks. That’s basically what I was thinking ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 6, 2025, 10:48pm UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/17 "2025-02-06T22:48:50Z")
Found a more explicit quote, from Babylon’s Ashes (book 6), referring to Ceres: > The administration levels were out nearest the skin of the station where the Coriolis was least pronounced. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 8, 2025, 12:46am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/18 "2025-02-08T00:46:03Z")
And later - still talking about Ceres: “And with the radius of spin as big as it was, the Coriolis should have been negligible.” ---
**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\ **Post date:** [February 8, 2025, 1:54am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/19 "2025-02-08T01:54:14Z")
I think it’s moe the gyrscopic force than coriolis. Coriolis like cetrifugal is a “phantom force”, apparently the extrssion of a rotating frame of reference from the point of view of someone inside that rotating reference. You throw a ball parallel to the axis of the giant cylinder for example and to you it appears a force is pushing it sideways. It’s just staying going straignt and you are moving rotating with the cylinder. Watch this: [https://www.youtube.com/shorts/](https://www.youtube.com/shorts/) with the video 0HFO8oHqOLc which I can’t embed. The same forces affect the fluid in your inner ear. You turn your head in a rotating frame of reference, and your inner ear balance tells you that you are turning in a different direction. You can get this same effect in those carnival rides where you are in a drum pressed against the wall as it rottes quickly. Try turning your head and you may find your ears disagreeing with your eyes -which for some can induce nausea. Arthur C Clarke discussing the filming of _2001_ mentioned to avoid this disturbing effect, a rotating cylinder (like the centrifuge in _Discovery_ ) had to be 300 feet diameter at 1 G. He also mentioned they solved this issue in the film by simply ignoring it. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [February 8, 2025, 2:05am UTC](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792/20 "2025-02-08T02:05:44Z")
> [@md-2000](#): > > which I can’t embed. Here you go [![](https://img.youtube.com/vi/0HFO8oHqOLc/hqdefault.jpg "Angular Momentum Bike Wheel Demo - Short version") ](https://www.youtube.com/watch?v=0HFO8oHqOLc) [Next page](https://boards.straightdope.com/t/coriolis-effect-and-location-inside-a-spinning-object/1013792.md?page=2)