Questions tagged [earth]
Earth is the planet on which we live, the 3rd planet from the Sun. Questions using this tag should be about Earth the planet and not Earth-like planets nor earth, as in dirt or soil.
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How much does temperature affect the time of sunrise?
Please forgive me if this is a dumb question, or if my understanding of basic physics is wrong. Please feel free to correct me.
As I understand it, if the Earth didn't have any atmosphere, then the ...
0
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1answer
43 views
How fast would an object at cruising altitude (around 10,600 m) need to travel to stay on the opposite side of the Earth to the Moon? [closed]
I am trying to figure out how fast an object will have to travel (at a height around 10,600 m) to never be in the presence of the moon. Meaning the object will always be on the opposite side of the ...
3
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1answer
90 views
Did Eratosthenes make his measurements on the same day?
Erasthosenes measured the circumference of the earth on the summer solstice by observing the sun at Alexandria and Syene.
Was this done on the same day in one year or on the same day in two ...
2
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1answer
48 views
If I drive East, how much lighter am I than if I drive West?
I'm at the equator. Suppose I am driving at x kph, in the direction of the Earth's rotation (i.e. due East), I presume that the force my vehicle exerts on the ground is less than when I am stationary. ...
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0answers
27 views
Volcanic Eruption Calculation? [migrated]
So, I was trying to find the amount of energy created during a volcanic explosion, I have been looking around, There was one calculation I saw where I should use the Kinetic Energy which is $E_k=\frac{...
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1answer
41 views
How does the Earth's radial acceleration affect it's velocity during orbit around Sun? [closed]
When the earth moves along its ellipse at $67,000mph $ it accelerates at $0.006m/s^2$ would it be correct to say it's speed at some points relatively increases by $0.006m/s$ every second
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1answer
39 views
What's the Earth's linear acceleration component around the Sun?
The earth's centripetal acceleration around the Sun is $0.006m/s^2$ does this mean one can say the earth's acceleration when it travels(revolves) at $670,000mph$ is simply equal to its centripetal ...
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39 views
Large objects in the universe sized by gravitational and electrical constants
In a famous talk (from 14:30 to 15:00) Nima Arkani-Hamed tells us that what "fixes the size of the earth" is the equilibrium between the gravitational pressure against the atomic pressure of the atoms ...
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Eratosthenes experiment but with three wells
In this video Neil Tyson mentions that the shadows of three wells are consistent with a round-earth + far sun model, and not with a flat-earth + close sun model.
He didn't go into specifics about why....
3
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2answers
90 views
Does current flow when you connect a battery to earth?
Let's say that the earth has 0V and everything is ideal,
does current still flow and why?
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0answers
20 views
Need an equation to calculate the list of latitudes and longitudes of an off-nadir sensor with a given half angle
I need a deterministic way to determine a list of latitude and longitudes of an off-nadir pointing sensor for a given half angle. Below is a depiction of the problem.
It isn't too hard to calculate ...
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1answer
84 views
Is gravitation on earth less in nighttime than in daytime?
I have been thinking on the effect of the centrifugal/centripetal forces from the orbital movement of the earth around the sun, which might perhaps affect the gravity.
In nighttime we are on the ...
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2answers
62 views
Is the period a physical observable in General Relativity?
I am currently seeing the classical tests of GR. To justify the introduction of a test based on the Doppler effect, the professor says that the previous test ( Shapiro and echo-radar test ) is based ...
3
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2answers
58 views
Is one side of earth faster at night and slower at daytime?
I'm reading Physics for Entertainment by Yakov Perelman and in it he says under "When we move around the sun faster" that at midnight the speed of the rotation of the earth is added to that of earth's ...
1
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1answer
36 views
Measuring the earth's electric field
My question stems from a question on the Dutch VWO-level highschool state exam (from 1993) concerning a device to measure the earth's electric field. It consists of two plates positioned above one ...
5
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1answer
48 views
Is the Earth orbiting an 'illusory' Sun, owing to the 'speed' of gravity? [duplicate]
We see the Sun about eight minutes after light left it. Presumably this means we are also experiencing the Sun's gravity 8 minutes after it 'left' the Sun.
So are we orbiting around the Sun we can ...
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4answers
783 views
Is Earth an inertial reference frame?
Is earth considered as inertial frame? i was confused because we learned about coriolis effect. We know that earth spins therefore coriolis effect should take place . But does it have minimal effect ...
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2answers
29 views
Can magnets be arranged to interact with earths magnetic field to produce force?
Is it possible to arrange one or more magnets along with iron/ferric guides to interact with our planets magnetic field in such a way that a force is generated in one or more directions?
Would a ...
7
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1answer
470 views
How do we know the Earth's core is Molten with Seismology?
My current knowledge about how the core of the earth was discovered is the observation made from non returning/reflecting sonar signal when sent to deeper depths through the earth's crust/mantle. How ...
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0answers
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If the Earth would change into a ball of water, how wil its form develop, considering only the Sun's and Moon's influence? [duplicate]
Let's fantasize that the Earth changes in a non-rotating ball of water. And let's assume the only gravitational influences on it are those of the Sun and Moon.
What will happen to the form of the ...
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2answers
63 views
What happens to the water on the surface of the Earth if the Earth is not rotating about its axis in the Earth-Moon system?
Suppose the Earth is not rotating. As usual, the Moon follows its normal path around the Earth. Let's assume it's a circular motion and that there are no other gravitational influences.
A test ...
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1answer
50 views
A question about horizontal doppler effect on galaxy hydrogen radiation observation
The figure shows the positions of the solar and neutral hydrogen
regions A to D rotating in a circular orbit relative to the center of
the galaxy. The sun and A to D assume a Kepler rotation.
...
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2answers
77 views
Confusion about angular momentum of earth moon system
My assumed definition of angular momentum is the sum over $i$ of $L_i =r_i\times{\omega_i}\times{r_i}$ for each particle about some origin.
We have two spheres rotating about the centre of orbit. For ...
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3answers
79 views
How to calculate weight of an object orbiting another object?
How do we calculate weight of an object which is orbiting another bigger object in the space?
For example, comparing the pair of Sun-Earth, Earth is orbiting Sun due to the force applied by Sun on ...
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3answers
98 views
The acceleration in Earth's gravity
The acceleration in earth's gravity is $9.807 m/s^2$ at my location. But is this value uniform in the entire earth? For example in the inner core or outer core. What is the acceleration in the center ...
3
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1answer
60 views
How much does NASCAR affect the rotation of the Earth? [duplicate]
Many of us will be familiar with XKCD 162: Angular Momentum, in which someone spins counterclockwise to slow down the rotation of the earth and make the night longer.
The mass of an individual human ...
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25answers
19k views
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 ...
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0answers
46 views
Would the formation of the Mediterranean sea be enough to shift the Earth on its axis?
According to this article, the Mediterranean sea was formed when the Atlantic broke through (what is now) the Straits of Gibraltar, and flooded the basin.
Assuming that is correct, and also that the ...
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1answer
36 views
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:
...
2
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2answers
85 views
Innermost stable circular orbit in Schwarzschild solution
I've been reading about GR recently and I can follow the derivation of a Schwarzschild solution to it's final and well known form in Schwarzschild coordinates.
The orbit stability argument (for a ...
0
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1answer
39 views
Measured Earth local gravity
I am looking for measured data of the local gravity on Earth. I know this website (https://www.ptb.de/cartoweb3/SISproject.php). The idea is nice but it looks a bit old and I would like to have an ...
6
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2answers
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Blocking of infrared radiation from the sun by $\rm CO_2$ [duplicate]
Why is the infrared heat from the sun not prevented from entering the earth's atmosphere by $\rm CO_2$ to the same extent that it is prevented from leaving the Earth's atmosphere?
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3answers
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Direction of Coriolis force [closed]
My doubt is all about finding the direction of coriolis force by using the direction of the moving object. I really find it difficult to determine the direction of coriolis force through direction of ...
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4answers
67 views
Is there any way looking at Stars from that I can understand that we are revolving around the Sun?(Not caring about other planets for now)
I am learning Astronomy. I videos or lessons I look at are already biased over heliocentric math to explain the parallax concept. I am looking for an intuition to get myself a deeper understanding of ...
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4answers
232 views
What is acceleration due to gravity at the centre of the earth? [duplicate]
When I asked my teacher that what is the acceleration at the centre of earth, he replied that it is 0 as when we move inside the earth, the effective mass decreases i.e. the mass that exerts ...
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1answer
267 views
What would really happen if somebody dropped a small black hole into the Earth?
Suppose we drop a small black hole, but large enough that it accumulates mass more quickly than it radiates it, into the Earth. What happens? This question has already been asked here and here, but ...
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2answers
73 views
Do we see an ellipse when we view Earth's horizon?
I wanted to try to determine mathematically exactly how much curvature one should see on the horizon when I viewed it from a given height, and it hit me that looking at the horizon is not the same as ...
2
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2answers
131 views
Why doesn't Foucault's pendulum show Earth's spin at the equator but works at the North/South poles
If you where directly above the North/South pole and set up Foucault's pendulum, why does it show the Earth's spin even though the Earth isn't spinning there? This is also where it takes the shortest ...
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1answer
45 views
How can we have different speeds relative to a same point for a same object?
A day last not the same at all altitudes (https://aapt.scitation.org/doi/10.1119/1.5000802), meaning earth has different angular velocities.
What is the actual rotation speed of the earth to the ...
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1answer
44 views
Detecting Earth’s Changing Speed Will My Idea Work?
Is there a way to detect the earth’s changing speed as it orbits the sun? I’m thinking of an at home experiment. It would be a plumb bob suspended in a tube about ten feet in length. There would be a ...
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1answer
36 views
Microwave links
If the record for microwave links is 235km long, and the microwave waves must travel in a straight line (and cannot go through solids such as the sea or objects in between), then how did they account ...
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2answers
64 views
Life around a different element from Carbon [closed]
On Earth, life developed around Carbon (and Hydrogen and Oxygen). I guess this depends on the availability of those elements, but also on the spectrum of radiation and Temperature and Pressure. Under ...
0
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1answer
51 views
Cutting of Magnetic Flux
My book reads :
If a player runs along north south direction, no magnetic field lines are cut.
So my question is that how is this possible because the vertical lines are still perpendicular to his ...
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2answers
69 views
Day/Year Length Of Larger, but same mass, Earth? [closed]
I’m wondering how the length of a day and year would change on Earth if it was twice as big, but the same mass (less density)?
Also, would such a difference cause it to orbit closer or further from ...
3
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3answers
127 views
Earth's rotation in an empty universe
I have read these questions:
Is rotational motion relative to space?
Rotation in an 'empty' universe
None of these talk about whether we can and how we can determine rotation of Earth ...
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3answers
148 views
About Entropy Definition
I quote the coming lines from Igneous & Metamorphic Petrology by Myron G. Best (2003):
One statement of the second law of thermodynamics is that spontaneous natural processes tend to even out ...
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1answer
73 views
Gravitation question
I’d like to ask the following doubt that came to me after some exercises:
Is it possibile to exactly establish,given a satellite orbiting Earth with a certain $\vec v_{0}$ and distance $\vec R_{1}$ ...
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0answers
30 views
Spherical harmonic about normal mode
Since spherical harmonic could describe the normal mode on spheroid(like Earth),
I want to ask why the order m must between degree -ℓ ~ ℓ?
I can understand it by the math during the proof process, it ...
0
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3answers
45 views
Since astronomers are adding 'leap seconds' to our years nowadays, does that mean Earth's orbital period is getting longer?
How long was an Earth year several billion years ago? (I'm assuming constant days, even though I know days were much shorter back then).
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1answer
71 views
Why does not the Moon escape from the Earth? [duplicate]
We know that Gravitational Force that is applied by the sun on the moon is greater than that by the earth on the moon.
My Question is then why does not the moon escape from the earth and go towards ...
