All Questions
20
questions
0
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1
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59
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What is the hydrostatic shape of an ideal rotating planet? [duplicate]
It is a well-known fact that rotating planets have a flattened spheroidal shape. However, the NASA site says about Haumea:
The fast spin distorts Haumea's shape, making this dwarf planet look like a ...
- 866
0
votes
3
answers
345
views
If the Earth rotated slower about its axis, would your apparent weight increase or decrease?
The title above was a question on an exam that was marked wrong for me. I answered that if the Earth rotated slower (i.e. longer days), my apparent weight would increase. I based this on the ...
- 135
14
votes
9
answers
7k
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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 ...
- 427
1
vote
3
answers
262
views
Does gravity cause the Earth's equatorial bulge?
The way I understand centrifugal force, I don't see how Earth's daily rotation alone would cause equatorial bulges to form. The usual explanation is that the centrifugal force increases with distance ...
- 31
0
votes
2
answers
106
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What force accounts for Earth's equatorial bulge in an inertial frame of reference?
I am confused as to how Earth's centrifugal effects from its daily spin can be explained from an inertial frame of reference relative to the distant stars. The usual explanation is that the ...
- 31
1
vote
1
answer
88
views
What would happen if the Earth rotated at the rate required to achieve orbit at its radius? I.e ~7k m/s instead of ~460 m/s
To achieve a circular orbit, you need to have a velocity of $$v = \sqrt{Gm/r}$$ which is about 7 km/s at the Earth’s radius, but the Earth’s rotational speed is only about 460 m/s (by taking the ...
- 111
3
votes
2
answers
175
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On a Torus World and the force upon inhabitants
I am looking into torus worlds for fiction, and I know how to calculate the necessary speed to rotate, and necessary radius, for such a world to get a specific force of gravity.
But what I am ...
- 221
0
votes
2
answers
214
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Simplest expression for gravitational flattening of Earth-like planet, from zero rotation rate to Earth rate, to within 10 percent error
Richard Fitzpatrick discusses the rotational flattening of a celestial body. A model that assumes homogenous density arrives at a difference between the Earth's equatorial and polar radii of 27.5 ...
- 21.4k
9
votes
11
answers
5k
views
Can a person on the equator jump up higher into the air at sunset than at sunrise?
I am wondering if a person on the equator can jump up slightly higher into the air at sunset in comparison to jumping up into the air at sunrise.
The reason for this would be that at sunset the Earth ...
- 478
0
votes
0
answers
51
views
Centrifugal pressure of the inner core towards the outer core of the Earth
As we go towards the center of Earth the gravity weakens. Does that mean that due to absence of gravity the outer part of the inner core exerts a pressure against the inner part of the outer core of ...
- 2,255
3
votes
1
answer
184
views
Is the apparent gravitational force on certain parts of a rotating spherical planet off centre?
For a person standing at the equator, if he sees an object in free fall, he will see that the object accelerates downward at the rate
$$a = g - \omega^2R$$
where $R$ is the radius of the planet and $\...
- 1,931
0
votes
1
answer
402
views
Why do we weigh less on equator when centrifugal force isn't a force at all? [duplicate]
Why would we weigh less on equator as the weighing machine measures the force by which we push ground and that should not change if are on equator or poles?
user250074
9
votes
7
answers
5k
views
If the mass of the Earth is decreasing by sending debris in space, does its angular momentum also decrease? [duplicate]
We are sending huge amount of debris into space from earth, and also very heavy satellites and rockets, then the mass of earth must be decreasing over time.
If the mass will decrease, then ...
- 213
0
votes
0
answers
26
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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?
- 1,648
2
votes
1
answer
92
views
Earth bulge and axis precession
We know that earth is not spherical because it spins. Does every object that spins bulge? for example a rotating wheel bulges? Also how moon and sun create the torque that shifts the axis of rotation (...
- 1,648