# Q: If the world were to stop spinning, would the people and everything on it be considered ‘lighter’ or ‘heavier’? Would any change take place? And does centrifugal force have an effect on gravity?

Physicist: Centrifugal force* due to the spinning of the Earth is certainly a measurable effect, but it’s a small effect.  While the spinning of the Earth doesn’t directly affect gravity, it does off-set it a little.  At the north and south poles objects weigh exactly what they should, and at the equator things weigh slightly less.

Assuming that the Earth is round (which is a pretty good assumption), with a back of the envelope calculation you can figure out the centrifugal force trying to fling you into space.  At the equator (where it’s strongest) that force is approximately 0.35% as strong as Earth’s gravity (0.0035 g’s).  So, if you weigh 300 pounds in Ecuador you’ll find that you weigh almost 301 pounds at the Amundsen-Scott South Pole Station.  0.35% doesn’t seem like much, but it would have a profound affect on at least a few historical events.

Centrifugal force always points out from the Earth’s axis, whereas gravity always points toward the Earth’s center.  So you’d think that somewhere between the poles, where the centrifugal force is zero, and the equator, where it points straight up, that there would be a place where it points a bit sideways.

The farther you are from the Earth’s axis the more centrifugal force you’ll experience. At a latitude of ±45° it pulls sideways more than anywhere else.

Turns out, that place is at 45° north and south latitudes where you “should” find that things get pulled sideways with a strength of half of the maximum: 0.17% g’s.  If the Earth was perfectly round, then this would be exactly the case, and everything in Europe would have to be built slightly tilted (if you’re wondering, the Tower of Pisa would be leaning the wrong way).  However, fluids (and the ground is basically a fluid) move so that the net force always points directly into their surface.

A spinning trough of water. Gravity points down and is constant, while the centrifugal force points out and increases with distance. The surface of the water is always perpendicular to the combined force.

By being distorted a little (an extra 20 km at the equator) the combined gravitational/centrifugal force always points straight up and down.  So, if the Earth were to stop spinning right now then we’d find that buildings were tilted very slightly, things at the equator would suddenly weigh 0.35% more, and eventually the Earth would settle into a more perfectly spherical shape.

Now, if the Earth were to literally come to a sudden and abrupt stop: that would be lots of bad. Things at the poles would be fine, but the closer to the equator the greater the change in speed.  At the equator everyone and everything would suddenly find themselves moving east at mach 1.4 (1,038 mph), and every land mass near the equator would be thoroughly scrubbed by the oceans washing over them.  The economy would take a real hit if the Earth suddenly came to a stop.

*Any time that centrifugal forces are mentioned in the vast crucible that is the internet, a small but vocal cadre makes it known that the centrifugal force isn’t really a force.  Be cool.

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### 50 Responses to Q: If the world were to stop spinning, would the people and everything on it be considered ‘lighter’ or ‘heavier’? Would any change take place? And does centrifugal force have an effect on gravity?

1. ivo says:

I saw recently a documentary on NatGeo or Discovey, not sure which one, about what would happen if the Earth’s rotation were to slow down and eventually stop. All sort of crazy weirdness happened, of course, but what shocked me the most were the huge bodies of water that would move from the equator to the poles and thus flooding everything in their path. Eventually, the poles would be covered in water and the only land would be a huge piece on the equator. You should try finding that documentary, it was really fun to watch.

2. Eamonn says:

Great article.

How fast would the Earth need to rotate for the centrifugal force produced at the equator to equal Earth’s gravitational pull? How short would this make the average solar day?

3. The Physicist says:

Assuming that we continue to assume that the Earth is round, the equator would have to be moving at about 7.9 km/s (orbital velocity at ground level). This translates to a day that’s about 84 minutes long.

4. Kirov says:

This made me think. If one was standing still at the North pole, then relative to space itself, they would be spinning. Would they get dizzy?

5. The Physicist says:

Exactly as much as standing on a merry-go-round that takes 24 hours to turn once.

6. The Wonderer says:

We would age faster though, wouldn’t we?

7. Khan says:

When the earth stop spinning, the value of g at equator will increase. Why?

8. Alicia says:

If the planet has more mass will gravity be lighter

9. AALOK RANJAN says:

On contrary to all above arguments If the rotation of earth is stopped then the magnetic field that is gravity will vanish as the gravity of the earth is due to the metals present at the core which produces magnetic lines of force these are generated due to the difference in the velocity of core and mantle. As soon as the earth’s rotation stops the gravity will disappear.

10. Andy Harris says:

“As soon as the earth’s rotation stops the gravity will disappear.”

The magnetic field might slowly dissipate (thus killing us all) but the Earth would still have the same mass and therefore the same gravity field.

11. steve says:

Wake up. The earth doesnt spin, rotate, or move. The earth is stationary. Multiple scientific experiments have been done and are easy to do your self to prove the earth is stationary. Secular science needs the earth to move to propagate their lies about a huge universe, big bang, evolution etc…

12. Andy Harris says:

The remarks by Steve “Wake up. The earth doesnt spin, rotate, or move. The earth is stationary…”

Pity he doesn’t leave more of an explanation for his beliefs. I’d really like to see that including details of the “experiments” he speaks of.

13. oca says:

so what if the earth stops spinning?if that happens,what can you do about it?right now,it might make an interesting topic.but,does it matter?what interest me more are mundane problems like converting sea water into clean fuel, or making it fresh for drinking,how to grow more trees by reforestration,how to have fast, clean and safe transportion,and etc.but doing anything scientific to stop the earth from its natural state,forget it.we are being distracted from the important issues.san blague,there are many important things to talk about.ca va?

14. Buck Rogers says:

Please, stop the world and let me off of it.

15. seth says:

So we all have a center gravity die glocke Butler’s weapon now time travel wouldn’t actually be time travel jest airplanes are fast but they are not attached to the ground but the bell was and to match it it with earth that’s we are allready moving that fast to center ur self inside but actually be moving like we are ow would it slow time

16. Thomas says:

Steve, I would really like to know what experiments I could do that proves your theory that the earth doesn’t move. Since you’re claiming it can be done very easily I’d love to conduct this experiment put it on youtube and collect my Nobel Prize. Oh, and the subseuent tornado of cash I’d recieve for having this new information quoted in journal articles and textbooks. So, please if you could tell me how I can help prove your statement I would totally give you credit when I type up the article.

17. Hans Geiger says:

Being the devil’s advocate for Steve.. possibly the Michelson-Morley experiment proves a stationary earth as they did not scientifically detect ether? After all, it was the great Michael Faraday that realized the relativity of it all.. an electric current is generated either by a moving coil of copper over a stationary magnetized iron rod or equally – it can be generated by a moving magnetized iron bar through a stationary coil of copper. I cannot prove we are not the center of the universe. If we are not – which of six pointing directions is closer? the mathematics of a fast sun racing across the sky of a stationary earth probably matches the math of an orbit earth around a stationary sun. 1/2 would still equal 8/16 by any other name…

18. Roy says:

If our planet were to suddenly stop spinning, the least of our problems would weighing a little bit more. To wit…

1. First, let’s just ignore that the energies applied to cause such a massive change in momentum would rip the crust away from the mantle and convert the planet a molten state causing the immediate extinction of all life down to and including the microbial level.

2. The sun would heat only the side of the planet with its face toward it, baking it until all life dies. The dark side of the planet would freeze to death. Everything in between would be killed by storms resulting from the changes to the weather. Any life that managed to burrow deep and avoid an immediate death would probably die when the Earth’s atmosphere burns off completely.

3. We would lose the magnetic field that protects us all from hard radiation from the sun. But, we would all be long dead before that became a problem.

So, yeah… it would be a “bad thing”.

19. Benjamin says:

Regarding steve’s comment. I am christian and still believe in the big bang, Earth orbiting the sun, etc. The “feeling” of being stationary is simply due to the vastness of our beautiful cosmos. No one can wrap their mind around the size of the Universe.

Oh, and if you want to clarify for your case, could you give me a link to the evidence to suggest that Earth is stationary?

20. Dara O. says:

I don’t really get this whole centrifugal/centripetal malarky but what I really want to know is how centripetal forces affect gravity.

21. Flaming Svin says:

If gravity were to disappear would the centrifugal force makes the objects flew into space possibly objects at the equator?

22. Sharl says:

Thomas, Steve is 100% correct that the earth is not moving. It is standing still.
I found that debating doesn’t change anybodies believe. Wether it is scientifically wrong or right. I am merely stating the fact.

Lets look at another facts which, when you really look into it, opens up the whole can of worms.
The earth is not round as a ball, but flat like a disk or pizza. The sun and moon moves in a circule around above the earth. The sun and moon is at equal height, about 5000 km away from the flat earth surface. The diameter of the sun and moon is the same, about 50 km in diameter. The stars and planets is extreamely small and moves in a circule aroune the star Polaris, which always stands still in the sky. Doesn’t matter what day of time, season, or year.

If you realize the earth is flat, then you ought to know that the whole concept of satelites can’t be true and is also a lie. They don’t exist. Wheather baloons, detailed enough to fool all of us.

No man or object have been launched into outer space, because it is impossible. We haven’t been to the moon, or send stuff to mars. Fairytale my friends. Why can’t you send a man to the moon and back. Because if you take all the fuel required to do so, you would be to heavy. This is an equation which can’t be ballanced.

Why is every nation on earth faking space travel and launching supposed satelites and participating in supposed space missions? Now you are asking the right questions.

23. DAN says:

I would like to hear Sharl’s amazing perception of how seasons are caused and why certain stars can only be seen at certain times of the year due to our location within our solar system. Why create such lies if it wouldnt make a difference otherwise. Science always breaks through with the truth. Sharl i call you out to reference any evidence or mathmatical explanations to justify your theory.

In this world, dreams are dreams, religion is trust and science is truth. Let the scientist do what they do best, and we will leave you with religion. thanks

24. Keith says:

Sharl, I believe, is just trying to show people how educated some people that believe in that edited Jewish fairytale. Obvious clues, like bad spelling, basically pointing out that gps and satellite tv are just faked, and the general impression I got from it was that someone was laughing their heart out while writing it.

25. Taylor says:

“Centrifugal” force doesn’t exist. There is no such thing as an outward-seeking force… The feeling of some outward force when traveling in a circle (such as in a car that’s turning) is due to your body’s natural tendency to keep its motion; in other words, inertia.

26. Stephen says:

“Centrifugal” force is perceived but does not actually exist. Think of like those rides at fairs where your in a rotating room and pressed up against the wall and can’t move. It feels as if you are being pushed against the wall (the perceived centrifugal force) when actually the walls are keeping you from flying outward by pushing you inward (the actual centripetal force).

27. Joe Martine says:

Given a “loosely” known rate at which the earths rotation is slowing, how long backwards in time would it take to the point where the forces to catapult an object off the surface at the equator would be greater that the force of gravity itself?

28. Sajid says:

Well good to hear that. But clarify 1 thing. Isnt gravity due to the cetripetal force produced by the revolution of earth in its orbat around the sun?

I’m a M.Sc physics Student. And astronomy is my subject.

30. The Physicist says:

@Sajid
Nope. The centrifugal force of the Earth’s movement around the Sun is what keeps us from falling into the Sun. Gravity is strictly caused by the presence of matter (and energy).

31. lee says:

For starters the earth must spin on a axsis i think water is what stops us from going too fast or slow (example if you spin round with your arms out stretched then pull them in tight you go much faster so if the earth started to spin faster the water would move towards the equater an slow us down same as if we went too slow the water would recede to the poles and speed us up but what holds us in orbit round the sun i know its because were orbiting at a higher speed than gravitys pull but what keep us going at that speed could it be the moon

32. i understand a whole lot of mathematics. how realy and nearly can i get to understand the problem relating to the imaging of worlds spinning or the world standing still as you guys are saying?? am quit bt a great guy in african kenya.

33. Afsar Husain says:

I think we live in a web of electromgnetic field spun by the SUN, around which all planets move in a specified orbit by virtue of three dimensional motion of gasous /molten metalic mass in theSun ?…similar to a magician who hold different balls attached with a string, and he spins all of them in a unique way. The sun has nuclear fission frequently in its round confinement resulting into light and fusion of electromagnetic waves into the space. The motion of sun makes all its planets move in their orbit as also spining themseves. If motion of sun retards then catastrophe on all planets shall occur.

34. katleho paeea says:

What keeps the earth to orbit around the sun at the same speed is the universal gravitational force pull (G) between the centre of the two bodies and the square of the distance between them…qwaba!

35. Yakubu says:

Well, having read all your comments,one thing we should have in mind is that there’s movement of either the sun or earth which of course results in day and night.but how the movement takes place is what we study and calculate

36. Tusharkanta Behera says:

I want to ask that if we put an object on the surface of a globe and revolve the globe why the object fells down ?

37. Jeanette Nicole says:

WHY DOES THE DURATION OF THE SOLAR DAY VARY SLIGHTLY THROUGHOUT THE YEAR ?

38. Chris g says:

I would like to know how much faster the earth was spinning 200 million years ago and how much you would weigh at the equator. Not being a physicist, my unscientific math puts the moon around 5000 miles closer when dinasaurs showed up. Given the earth and moon are for this purpose a closed system, the law of conservation of angular momentum would say the earth was spinning much faster then and is slowing as the moon moves away from earth. Why am I asking? I came across a debate started by Jose Canseco that Dinasaurs were big because gravity was “alot less”. Arguments against him stated that the size differential between mammels back then did not line up with the “less gravity” theory. However, from what I see, depending on whether it evovled at the equator vs. closer to the poles, a significant difference in gravity would be present back then. And of course, this is my own uneducated theory, so don’t be too harsh with replies

39. Jer says:

For those who still think the earth is flat and the center of the Universe we have NASA photographs from the Cassini space probe that show that it’s round, spins, and is very small in the solar system.
http://www.space.com/22047-earth-moon-photos-from-saturn-mercury.html

It’s true from our vantage point on a spinning sphere it looks like the sun “rises” and “sets”…but from decades of astronauts videoing their orbit around the earth we can see the sun isn’t moving at all—it just us.
https://www.nasa.gov/multimedia/imagegallery/image_feature_2167.html

40. basit abdul says:

I think gravity of earth is due to the spinning motion of earth as we create artificial gravity in the satellites by spin the satellite in its own axis with particular frequency

41. Andy Harris says:

I think you’ve completely misunderstood what causes the gravity effect on Earth (and other objects with mass) as well as why the effect can be mimicked (to some extent) by rotating vessels (like a space station for instance). Firstly, there is no such thing as gravity as a force. It is an illusion. What we perceive as gravity is actually acceleration due to the curvature of space caused by any object with mass. Even your mass causes space to warp however the effects are so small as to be almost zero. For a mass as large as the sun, the Earth, etc then this curvature is sufficiently large to induce a measurable acceleration. When a space station rotates it is using centrifugal forces to create forever changing angular momentum which gives an acceleration that we perceive as a gravity effect.

42. Ashamed says:

43. Marc says:

Is the earth’s gravity directly proportional with the size of life? I sometimes wondered if the existence of such large dinosaurs was because of less pressure exerted on the skeletal structure with less gravity. If the less gravity was because of a higher speed in the rotation, that would also explain the older ages in the bible. They could have been just as old as todays men but just more rising and setting of the sun. Any thoughts?

44. Kelly says:

Andy, if mass had very little (or no effect) the moon would have even less gravity than it does (due to the fact it does not rotate on any axis). The reason a spinning space station generates “gravity” is because it is inclosed. If you were standing on the outside of a spinning station you would fly off. The inside of the outermost wall (the wall directly opposite of the point of rotation) holds you in. You are basically getting pushed outwards towards that wall, emulating a gravitational effect.

45. Charles says:

Is the earth actually heavier because it is rotating? Suppose we propose to park the earth in an orbit a little further from the sun, to counteract the effect of global warming caused by greenhouse gases. Say we move the earth to an orbit of exactly 378 days, which divided by 7 gives 54 weeks per year, with no leap days. Would it take less total energy to spin the earth down, move it out, and spin it back up, or just move it spinning? The spinning adds inertia but not mass, however the effect of the spinning is to seem like it has higher mass. Thus a spinning object does not have equal inertial and gravitational mass. Is this a case of M(g) =\ M(I), thus opening a possibility of limitless acceleration by forcing M(I) to approximate zero while M(g) remains the same? Newton’s law says, F = d(mv)/dt, but the m in that law is the inertial mass, not necessarily the gravitational mass.

46. Charles says:

Concerning Charles comment. If F = d(mv)/dt and we expand that out, we get ,
F = v dm/dt + m dv/dt. Now consider the first term on the right side. If dm/dt is negative, then it adds to the left side, or the F side. To make dm/dt negative we have a saucer shaped object at the surface of the earth and spin it up on the surface. Then when we wish to take off we merely spin it down. That reduces inertial mass. Note that the effect is augmented by the velocity of the object. Thus the object would take off vertically , the right hand rule, and actually produce more acceleration as it rises, for two reasons. The velocity becomes greater and the m term in the second expression on the right gets less, because it is the inertial mass in the equation. Thus acceleration becomes very high. Eventually it would be only the payload mass, and no mass for liquid oxygen, liquid hydrogen, motors, fuel tanks etc.

47. Chase_Elliott says:

I got a little annoyed at the preachers singling out “centrifugal force” is not a force. Bore off. It’s correct English for the explanation of ‘centrifugal force’.

Electro magnetism is what’s classes as a ‘strong’ force, but doesn’t travel long distances. Gravity is totally unrelated to magnetism and it’s known as a ‘weak’ force, but travels long distances, proportionate to Mass 1 x Mass 2 divided by the distance between the 2 objects squared. We still don’t know how the energy of gravity transports through a space, but it is directly related to mass. Static or otherwise.

Newton’s entire point from the ‘Apple’ scenario was to explain how both the Apple and the earth were attracted to each other. Therefore, the apple was being pulled to the earth and the earth was being pulled to the apple.

48. Tony says:

If the earth would suddenly stop spinning would the 26 mile equatorial bulge cease to exist? Would the earth become a perfect sphere?