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0 votes
2 answers
65 views

How symmetric do we know the gravitation field to be?

Currently, the only ways to measure gravity is on quite large scale. So these experiments measure gravity averaged between vast systems of particles. Of course, such an averaging results¹⁾ in a ...
Ilya Zakharevich's user avatar
1 vote
1 answer
70 views

Tidal forces in the early solar system

I'm reading a book called "Gravity from the ground up" by Bernard Schutz. I don't understand this section from Investigation 13.3 on page 159, which discusses the formation of the solar ...
user3327311's user avatar
1 vote
3 answers
100 views

Escape Velocity from Moon to escape Earth-Moon System

So the escape velocity at Earth is roughly 11.2 km/s, but with the escape velocity of the moon it says that it is 2.38 km/s but since the moon is orbiting the Earth, wouldn't the effective escape ...
Roghan Arun's user avatar
  • 1,534
0 votes
1 answer
78 views

What happened to Newton 3rd law if our Moon is moving away at 1.5" yearly? [closed]

Our Moon is going away and I read that it is the culprit is our ocean, but then what happens to Newton 3rd law there should be an equal and opposite forces too so where's that? Is it absorbed by the ...
user6760's user avatar
  • 13k
0 votes
1 answer
32 views

Inquiry Regarding Hypothetical Celestial Mechanics Scenario

How would the addition of a second sun, located at the other focus of the planet's elliptical orbit, impact the motion and orbit of the planet? Specifically, how would the gravitational forces from ...
user avatar
1 vote
2 answers
153 views

Is a satellite revolving in Earth's orbit also affected by the gravity of the Sun or other planets?

The Earth revolves around the Sun and a satellite also revolves around the Earth. The Sun has a gravitational effect on all celestial bodies, so does it also have an effect on the satellite? If so ...
Vidushi Aggarwal's user avatar
5 votes
4 answers
562 views

Escape velocity when Sun is present

When we calculate escape velocity for an object from earth, what we do is, we conserve energy. So if $v$ is the escape velocity, we write $$-\frac{GM_em}{R_e}+\frac{1}{2}mv^2=0$$ since we are assuming ...
a_i_r's user avatar
  • 361
0 votes
1 answer
95 views

Why does the Earth move away from the Sun?

From the (Wikipedia's) definition of the astronomical unit $AU$, we have that it is defined as: $AU=\sqrt[3]{\dfrac{GMD^2}{k^2}}$ Where $k\approx0.01720209895$ is Gauss' gravitational constant, $G$ is ...
Antoniou's user avatar
  • 495
0 votes
1 answer
82 views

How to calculate Earth's speed due to moon induced orbit? [closed]

In https://stackoverflow.com/q/75297814/ the answer for the problem was that the earth like the moon had a speed due to the moon induced orbit. I don't understand how this was calculated? I have ...
Beckham's user avatar
3 votes
2 answers
529 views

Does the Sun or Moon affect weight measurements on Earth?

The gravitational acceleration due to the Earth at its surface, $g_E$, is $$g_E = 9.8\hbox{ m/s${^2}$}.$$ The gravitational acceleration due to the Sun at the Earth's position is $$g_S = 5.9 \times 10^...
John Eastmond's user avatar
1 vote
0 answers
55 views

Moon, Earth and the Sun [closed]

How to prove that the geometric locus of the points where the attractive forces of the Sun and the Moon are of equal intensity is a sphere of radius $ r = \frac{R \sqrt{Mm}}{M-m } $, where $M$ is ...
Physics19972509's user avatar
0 votes
1 answer
327 views

How do the planets stay in their orbit? [duplicate]

The Sun has a strong gravity. The planets also have gravity. So they attract each other. But then why dont they go and mix up with the Sun? If it is the orbit of the planets or a pre-existing motion ...
Arafat's user avatar
  • 15
1 vote
2 answers
86 views

How do we know orbits go in an elliptic shape?

I never really understood how we found out the orbits our planets follow are elliptical and not in a circle.
schrodingerscat's user avatar
2 votes
1 answer
238 views

Delta v of a trans-Mars injection (TMI)

Why does it only take about 600 m/s more than Earth's escape velocity to have an encounter with Mars while it takes much more Delta v (about 3 km/s) from a solar orbit (same as Earth orbit) to have an ...
Sebastyen Laroche's user avatar
13 votes
3 answers
2k views

Is it possible for a moon to have the same orbital period as its planet?

Is it possible for a planet to take just as long to orbit its star as a moon takes to orbit the planet? If we assume circular orbits, then $\text{orbital period}\sim \sqrt{\frac{\text{radius}^{3}}{\...
Ethan Maness's user avatar

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