Linked Questions

0 votes
1 answer

Why is the Earth not an exact sphere and what makes it bulge at the equator? [duplicate]

In chapter 7 of the Feynman Lectures Volume 1, Feynman explains that the Earth is round due to gravitation as everything attracts everything else. He also says that it is not an exact sphere since it ...
Osaid's user avatar
  • 29
1 vote
1 answer

The Earth's Equatorial Bulge [duplicate]

It is stated that the Earth is a 'squashed sphere' due to the very slight bulge at the equator. (Thought in reality it's such a small difference, it's essentially spherical) Typical values: ...
James Kwikje's user avatar
1 vote
1 answer

If Earth is oblate why don't oceans flow to the Poles? [duplicate]

The Poles are ~21 km downhill from the equator in a spherical coordinate system. So why doesn't water pool there?
cumfy's user avatar
  • 172
0 votes
1 answer

Correcting for oblateness of the Earth [duplicate]

I'm trying to model numerically the effects of the Earth's oblateness on satellite orbits. I'm seeing precession of the orbit, but not in the plane that I'm expecting. Here's my corrected grav. ...
DeltaG's user avatar
  • 257
2 votes
0 answers

How can we explain Saturn's non-spherical shape in terms of forces? [duplicate]

As we know the Saturn's shape is not spherical. In fact, its polar radius is almost 10% smaller than equatorial radius. This flattening is caused by the rapid rotation of this planet. Image credit: ...
Evgenii's user avatar
  • 151
1 vote
0 answers

Equation to predict the shape of a planet [duplicate]

I need help calculating gravity and shape of a planet based on a few factors. If a mass rotates quickly enough, the inertia (or "imaginary centrifugal force") will pull the mass outward "...
Iter's user avatar
  • 105
1 vote
0 answers

Estimation of Equatorial Bulge of the Earth [duplicate]

My dynamics lecture notes repeat the Earth's equatorial bulge can be approximated as: $$ \approx \frac{\Omega^2R}{g} \approx \frac{1}{300} $$ (Do they mean R/300?) They also include statements like: ...
Jhonny's user avatar
  • 683
0 votes
0 answers

Why spinning creates bulges? [duplicate]

Earth isnt a perfect but has bulges because of its spinning. What actually creates the bulges? Is the same reason that makes a liquid have v shape in a rotational tube?
Antonios Sarikas's user avatar
157 votes
27 answers

Simple check for the global shape of the Earth

I have been on a date recently, and everything went fine until the moment the girl has told me that the Earth is flat. After realizing she was not trolling me, and trying to provide her with a couple ...
SBF's user avatar
  • 1,431
57 votes
8 answers

Proof that the Earth rotates?

What is the proof, without leaving the Earth, and involving only basic physics, that the earth rotates around its axis? By basic physics I mean the physics that the early physicists must've used to ...
user8721's user avatar
  • 573
45 votes
7 answers

If the ground's normal force cancels gravity, how does a person keep rotating with the Earth?

When I am on earth, the weight of my body is countered by the reaction of the ground. So, there is no net force acting on me. But I am spinning with earth. But if there is no centripetal force then ...
Mockingbird's user avatar
  • 1,237
63 votes
3 answers

Why is the Sun almost perfectly spherical?

Relatively recent measurements indicate that the Sun is nearly the roundest object ever measured. If scaled to the size of a beach ball, it would be so round that the difference between the widest ...
user avatar
14 votes
9 answers

Is Earth really flattened at the poles because of centrifugal force?

My question is pretty much all in the title. I was always told that our planet is flattened at its poles due to the centrifugal force generated by its own rotation. However I don’t see how centrifugal ...
Federico's user avatar
  • 417
20 votes
5 answers

Why is Earth's gravity stronger at the poles?

Many sources state that the Earth's gravity is stronger at the poles than the equator for two reasons: The centrifugal "force" cancels out the gravitational force minimally, more so at the equator ...
sloth's user avatar
  • 517
11 votes
8 answers

Distribution of gravitational force on a non-rotating oblate spheroid

Suppose a person is standing on a non-rotating$^1$ oblate spheroid of uniform density. He first stands on one of the poles, then on the equator. In which case is the gravitational force greater? In ...
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