All Questions
20
questions
39
votes
5
answers
34k
views
Would you be weightless at the center of the Earth?
If you could travel to the center of the Earth (or any planet), would you be weightless there?
- 543
14
votes
4
answers
2k
views
What is the general relativity explanation for why objects at the center of the Earth are weightless?
The idea that as you move through the earth you get a symmetric cancelling of gravitational acceleration which approaches zero acceleration due to gravity at the center of the earth makes a lot of ...
- 1,039
10
votes
9
answers
4k
views
Why and when can the Earth be considered an inertial reference frame?
The question has been asked (e.g., here and here), but I would like to get a more definitive and mathematically formal answer.
The Earth rotates around its axis, around the Sun, and participates in ...
- 60.3k
7
votes
2
answers
1k
views
Does Earth experience any significant, measurable time dilation at perihelion?
Is there any measurable time dilation when Earth reaches perihelion? Can we measure such a phenomena relative to the motion of the outer planets?
- 79
2
votes
3
answers
543
views
How can we explain the position of Mann's planet when travelling on Miller's planet in Interstellar movie?
In the middle of the movie Interstellar, a crew of astronauts land on Miller's planet. For them only one day passed. For the one astronaut left on the station, 23 years passed.
Imagine both look at ...
- 103
4
votes
3
answers
11k
views
If the earth would stop spinning, what would happen?
What would happen if the earth would stop spinning? How much heavier would we be? I mean absolutely stop spinning. How much does the centrifugal force affect us?
If you give technical answers (please ...
- 321
-3
votes
1
answer
1k
views
Gravity anomaly in Lacnov, Slovakia: Gravity ashamed
http://www.youtube.com/watch?v=4qxwqNqL-Nc
http://tvnoviny.sk/sekcia/spravy/technologie/v-lacnove-sa-predmety-kotulaju-do-kopca.html
(Sorry: above links in Slovak.)
Can someone explain this to me? ...
- 121
2
votes
3
answers
31k
views
No uncertainty for standard gravitational acceleration?
The other day I asked about the uncertainty of light, and this issue triggered me to start looking into other physical constants and try to understand why other constants have no uncertainty.
One of ...
- 3,447
1
vote
2
answers
4k
views
How attitude indicator (gyro horizon) adjusts to the Earth's curvature?
Image a plane is flying from North to South and is crossing equator. How gyro horizon would maintain correct pitch angle? (Or East-West?)
I assume that pitch angle is correct at takeoff, so the ...
- 13
154
votes
14
answers
58k
views
How do I explain to a six year old why people on the other side of the Earth don't fall off? [closed]
Today a friend's six year old sister asked me the question "why don't people on the other side of the earth fall off?". I tried to explain that the Earth is a huge sphere and there's a special force ...
- 1,531
13
votes
2
answers
2k
views
Where did the energy released due to gravitational binding energy of the Earth go?
The gravitational binding energy of the Earth is $2×10^{32} J $, so the same amount of energy must have been released during the Earth's history.
According to this and this, the current internal ...
- 3,916
5
votes
1
answer
471
views
Could the Earth be ejected when the sun burns out?
My younger brother came home from school today and told us at the dinner table that when the sun burns out the Earth could be ejected from its orbit. Skeptical, I asked his source. He quoted his ...
- 184
5
votes
4
answers
8k
views
Could we make a trebuchet that could launch objects to a stable orbit?
Inspired by this xkcd, which calculated the energy requirements for accelerating individual humans to escape velocity (regardless of consideration for what that would do to your organs), I am ...
- 3,241
4
votes
2
answers
414
views
How do we age if we tunneled to Earth's core?
Scenario
Suppose there exists an advanced technology that can hypothetically transport living humans to study the center of the Earth, as they goes deeper underground most of the Earth's mass would ...
- 13k
3
votes
1
answer
1k
views
Electromagnetic radiation bending on Earth
Most articles say that a radiowave is able to propagate itself beyond the horizon because it is reflected off by the ionosphere (and the Earth itself).
But do radio waves also get bent according to ...
- 133