The Newtonian model of gravity in which the force between two objects is given by GMm/r^2.
0
votes
0answers
14 views
origin of cusps in simulated dark matter halos
I keep reading that cusps are one of the most "robust" predictions of N-body simulations of dark matter halos. But any paper I've found on the topic makes it sound like these simulations are ...
1
vote
1answer
82 views
Orbit of Earth around the Sun
Is there a way to show that motion of Earth around the Sun is elliptical (Kepler's 1st law) from Newton's laws without resorting to the use of differential equations of motion?
7
votes
2answers
134 views
Why is there no permittivity-type constant for gravitation?
When I look at electric or magnetic fields, each of them has a constant that defines how a field affects or is affected by a medium. For example, electric fields in vacuum have a permittivity constant ...
2
votes
1answer
64 views
How do we know the Earth orbits around the Sun and not the other way around? [duplicate]
I know that describing the trajectory of all planets in the solar system around the Earth is much more complicated than if we take the Sun as the reference point. But besides this, what is the ...
-4
votes
1answer
44 views
Value of of gravity 9.8m/sec^2 and centrifugal force [closed]
I had a doubt regarding centrifugal force on earth is not accounted in any equations as object falling towards earth.eg f=ma.i read questions asked by few about the same and got to a conclusion that ...
0
votes
2answers
80 views
Under what conditions, will a projectile motion follow a half circle?
What came to my mind is to throw an object far from the earth with a particular speed equal to $$V_{sat}=\sqrt{\frac{G\times M_{central}}{R}}$$like satellites. However, it would follow a full circle.
3
votes
0answers
64 views
How accurate is the patched conic approximation when performing a Hohmann interplanetary transfer? [migrated]
I've been making a Mathematica script whereby a spacecraft is transferred from Earth to Mars using a Hohmann interplanetary transfer by means of a patched conic approximation.
As far as I can tell ...
1
vote
0answers
68 views
Planatary motion of newtonian force [closed]
According to the Newtons gravity we can write,
$$\vec F = \frac{\hat r_{12} G m_1 m_2 }{r_{12}^2}$$ and we are well known that this law satisfies the planetary motions. What changes will we see if we ...
0
votes
1answer
50 views
Evaluating $v$ for orbiting a golfball [closed]
The curvature of Mars is such that its surface drops a vertical
distance of 2.0 meters for every 3600 meters tangent to the surface.
In addition, the gravitational acceleration near its surface ...
13
votes
0answers
207 views
How trustworthy are numerically-obtained periodic solutions to the three body problem?
This question is part of this week's Journal Club session.
I recently found out about the discovery of 13 beautiful periodic solutions to the three-body problem, described in the paper
...
1
vote
2answers
114 views
Determine if an object is in orbit
I am planning on doing a space simulation program with full physics and as part of a hack to avoid too many issues with number precision I was going to switch orbiting objects to a calculated orbit ...
0
votes
1answer
142 views
String tension in vertical circular motion
Suppose that I have a point mass attached to a massless string and I am rotating it vertically. That means The mass is in uniform circular motion and the path of its motion is vertical circle. How ...
1
vote
0answers
63 views
How can a single integral equal a triple integral? [migrated]
Here is part of a discussion about the gravitational potential of a sphere:
Let $dx$ $dy$ $dz$ represent an infinitesimal volume containing matter of density $\rho$ and mass $dm$. Then the ...
-2
votes
2answers
86 views
Explain what happens to object in lift [closed]
In the following image,three cases have been mentioned. N is the normal force acting on the object inside the lift and mg is the force of attraction. In second case, N = mg. In case 2, N = m(g+a) and ...
3
votes
0answers
95 views
Gravity - What happens when two objects of unequal masses fall freely towards the ground? (Revisited)
The common perception regarding what happens when two objects of equal sizes but unequal mass are allowed to fall freely towards the ground is that - both the objects make contact with the ground at ...
1
vote
0answers
32 views
Where are the L3, L4, and L5 of a hyperbolic orbit?
Do the L3, L4, L5 points exist in hyperbolic orbits? If yes, then where do they lie?
-2
votes
1answer
254 views
Details of the new solutions to the three-body problem [closed]
This question is part of this week's Journal Club session.
These systems look ridiculously fun to construct. Could someone explain the particulars? What are the various types of solutions, and ...
-1
votes
1answer
80 views
How does physicists calculate the gravitational self collapsing force of a star?
The nuclear fusion taking place inside the stars opposes its gravitational self collapsing force. But, how does physicists calculate it? I just know the classical gravitational theory and not a bit of ...
0
votes
1answer
48 views
Is the trajectory of the Moon around the Earth stable? [duplicate]
I understand how mathematically is possible to have one object with elliptical or circular orbit around another object in space.
so can I think of it as a limit cycle? If yes, then is it stable or ...
-3
votes
2answers
126 views
Why does a bicycle come to rest after travelling a distance?
According to Newton's law of motion, an object that is in motion will not change its velocity unless an external force acts upon it. In the case of a bicycle, if it is in motion with a certain ...
-1
votes
1answer
83 views
Does Archimedes law depend of lack of matter?
I would like to know if Archimedes law take in equation the lack of matter. Fluid density at 1. An object with density of 0 (or near 0) is put in liquid, it's fixed. The external sphere where liquid ...
1
vote
1answer
23 views
induction for massive objects
We know that when two charged bodies are kept near one another, they attract the charges and induce some charge near the surface. This happens even when only lne body is charged as the charges are ...
3
votes
0answers
61 views
What is the precise definition of Gravitational Sphere of Influence (SOI)?
I am trying to understand the gravitational sphere of influence (SOI), but all I get by searching is the formula that you can find on Wikipedia, that is
$$ r_{SOI} = a \left( \frac{m}{M} ...
-2
votes
3answers
74 views
Why heavier bodies produce greater gravitational pull than the lighter bodies?
The basic question "Why planets revolve around the Sun?", is explained by taking into account the heaviness of Sun. The lighter bodies are considered to move around heavier bodies,as like lighter ...
4
votes
0answers
49 views
Victorian cosmology after the second law of thermodynamics but before relativity?
In the 19th century, most astronomers adopted an island universe model, in which our galaxy was the only object in an infinite space. They didn't know that the "spiral nebulae" were other galaxies. ...
-5
votes
2answers
118 views
If there is no gravity, does that mean there's no mass as well?
I have demonstrated that weight only is measured based on the gravitational pull of where you live.
For example, the gravity on the surface of Mars is three times smaller than the gravity on the ...
2
votes
1answer
104 views
Is this object turn alone with torque inside disk of water?
This is not the original question, I changed for explain details. But now it's not possible to delete the question and now the reply is not in relation with question. I post a new question, and try to ...
0
votes
3answers
134 views
Why gravity decreases as we go under ground? [duplicate]
We all know that gravity decreases as we go upward, we also know that gravity decreases as we go inside the earth? I don't know why gravity decreases as we go downward or inside the Earth? Please ...
1
vote
0answers
24 views
The magnitude of spacecraft anomalous velocities?
That Voyager and several other spacecraft have had anomalous changes in speed is known. According to the news reports, the differences are unsettling. But just how large are these anomalies really? ...
4
votes
1answer
48 views
Variational principles: Meniscus
In determining the shape of a meniscus, we have to minimize the energy per unit length along the direction perpendicular to the cross-section of the meniscus:
$$\frac{E}{L}=\int^L_0 dx [\gamma ...
2
votes
3answers
172 views
How accurate is Newtonian Gravity?
I know that really fast moving things need Relativity rather than Newtonian physics.
I also know the quirk of the Mercury´s orbit.
But just how much more accurate is General Relativity than Newton´s ...
3
votes
1answer
56 views
Is it possible to levitate an object with piezoelectricity?
The delay for transmit pressure depend of speed of sound in the material. A lot of piezo slip-stick actuator can generate an asymetric wave. Like the differential pressure is not the same the force to ...
1
vote
1answer
47 views
Signs in proof of gravitation potential energy (GPE)
Proof of gravitational potential energy.
Work done by gravity in bringing mass from infinity to a distance of $r$ between masses.
When we use the integration formula and arrive at the answer we ...
0
votes
1answer
59 views
In a moving bus will the ball fall behind me when tossed?
Using Newton's law I have to find whether in a moving bus will the ball fall behind me when tossed in air or will come to me only or will fall in front of me. In fact there are two cases;
1- Bus ...
1
vote
8answers
378 views
Why in Newton's law of gravity, we do $M_1 \times M_2$ and not $M_1 + M_2$?
In Newton's law of gravity $$F=\frac{G M_1 \cdot M_2}{r^2}$$ we do the product $M_1 \times M_2$ and not the sum $M_1 + M_2$. Why's that so?
3
votes
1answer
186 views
Why closed bottle change its weight when I put effervescence tablet?
I use several shape, several type of material (glass, metal, plastic), I use two different balances with 0.01g of accuracy. I put oil on gasket, and put upside down (like that I can see if water ...
0
votes
1answer
64 views
Ball on a slope
I have a lab report ,but I can not write it in a correct way.
so, please help me to finish it ,because I need it tomorrow.
The lab experiment was about a ball rolling on a slope , I have a height of ...
3
votes
2answers
97 views
Mathematical model for this graph of a simplified binary star system?
Unnecessary background for question: I had a school assignment asking us to relate a quadratic equation to a real life example relating to our future dream career, making sure to express the accuracy ...
2
votes
3answers
151 views
Gravitational Potential Energy (GPE) to Kinetic Energy (KE) transfer in Satellite Orbits
I am stumped by a mundane A Level Physics question (teacher of physics here obviously a bit short of practice!). My colleagues and I are stumped and were wondering if any one could help us.
It ...
5
votes
2answers
75 views
How Galaxy is formed?
Given the distance among stars (the most massive objective in the space) is so huge, the difference of order of magnitude is about 7.
And also, since gravity is such a weak force, how is it likely for ...
1
vote
1answer
95 views
Gravitational binding energy and integrated potential energy not the same?
Before looking up the formula for the gravitational binding energy of a uniform sphere, I simply figured that the general formula for binding energy of an arbitrarily-shaped mass distribution would be ...
2
votes
1answer
41 views
What are the steps and energetic requirements for getting from the HST to the ISS?
There have been several general critiques of the realism some of the physics depicted in the movie "Gravity" notably regarding the the orbital mechanics of the transition from the Hubble Space ...
3
votes
3answers
111 views
Gravitational acceleration on the Moon and Mars
There are plenty of formulas that use gravity acceleration of Earth. This is represented with the symbol $g$. In my school work (I am a high school student) we usually take it as $g= 9,8 \,\text ...
0
votes
2answers
76 views
Is centre of gravity a point?
Is the centre of earth a point? If it is so, then it should attract objects both horizontally and vertically. But, it always attracts vertically. Why is it so?
8
votes
2answers
185 views
Intuitive explanation of why orbits are closed?
Yesterday my brother asked me how orbits work. Suppose for the sake of the question that you are trying to put a rocket in orbit around the Earth. I explained that orbiting is essentially being in ...
2
votes
2answers
97 views
Newtonian gravity equation in a 2 dimensional world [duplicate]
I am wondering if my line of thought is correct - and thus the resulting answer to the problem above would be correct.
As we know the gravitational force (of two point masses) is given by $$F = ...
0
votes
2answers
172 views
What is going on in the system? How are the formulas `mg sin(x)` and `mg cos(x)` derived?
When a load is resting on an inclined plane, there is force $mg \sin(x)$ that's vertical to the inclined plane and force $mg \cos(x)$ horizontal to the plane acting on it like this:
My textbook ...
1
vote
1answer
78 views
Orbital speed for a circular orbit?
I wanted to look up the formula for orbital speed for a circular orbit on Wikipedia, and I found 2 formulas:
All bounded orbits where the gravity of a central body dominates are elliptical in ...
13
votes
5answers
580 views
Can Helium Disappear from Earth?
Can Helium disappear?
As we know Helium is lighter than air, so basically Helium fly off from Earth.
Is it possible that in the future we will run out Helium?
4
votes
1answer
44 views
Do all celestial objects have stationary orbit?
Do all celestial bodies of sufficient mass such big asteroids, moon, planets etc. have orbit such that the period of revolution is same as the sidereal period of that object (such as geostationary ...
