The Newtonian model of gravity in which the force between two objects is given by GMm/r^2.

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How did Newton figure out the law of gravity? [duplicate]

How did Newton figure out the law of gravity? I know there are two other questions answering the same question but I did not understand anything from the answers Is there a third way of knowing how ...
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63 views

Physical Meaning of Cone used in Conic Section for Orbital Mechanics

Does the polar angle (complement of $\theta$ below) of a cone which intersects a plane to yield a conic section have a physical meaning in orbital mechanics? Note that the angle of incident ...
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33 views

Elliptical path of planets [duplicate]

Why are the planet's orbits in the form of an ellipse and what is the proof that earth moves in an elliptical path with the sun at its foci? Initially it was thought that earth moved in a circular ...
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3answers
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Are all trajectories parabolic?

I've heard this before, and it makes sense. Is it true? This being: Due to the effects of gravity and inertia, an object in movement not being acted on by any other force will form a parabolic curve ...
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If I make a object enter a planet's gravity it hits the surface with huge velocity, where is it gaining k.e. from?

If I make a object enter a planet's gravity range,it hits the surface with huge velocity,where is it gaining k.e. from? If i keep sending more and more heavy things like above and some how harness the ...
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3answers
131 views

How often does the earth rotate around the common center of mass with the moon?

I could not find anywhere how long does it take for the earth to rotate around the center of mass of the earth moon system, which is located inside the earth but off-center. And does this motion have ...
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79 views

Gravitational acceleration

'What is difference between free fall acceleration g and gravitational acceleration a?***a is with subscript g.In my textbook it is written that "free fall acceleration = gravitational acceleration - ...
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55 views

Sphere of electric charge revisited

I am thinking about a sphere of homogeneous charge distribution (see Electric field due to a solid sphere of charge, for example). Here we use a Gaussian surface (blue area) to find the electric ...
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2answers
73 views

Is it possible to apply Newton's equation of gravitation to attractive force between the moon and the ocean? [closed]

Someone was asking me how much force is acting on the waves when the moon is closest to the earth. Of course the first thing I tried to do is apply Newton's equation for universal gravitation $$F = G ...
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the torsion balance of the Cavendish experiment

I need to perform the Cavendish experiment and build a torsion balance but I can't find metallic spheres with enought mass so I was thinking about using a pair of dumbbells instead. My question is if ...
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2answers
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Why are L4 and L5 Lagrange points stable as points and not part of a circle?

I read this Phys.SE thread which is similar Why are L4 and L5 lagrangian points stable? but I did not want to necro that thread. It seems that most discussions of a three body problem are presented ...
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Would the Hubble Space Telescope be of benefit for optical astronomy at Lagrangian L5 point?

The Hubble Space Telescope will enter a decaying orbit in 2024. This is a physics based question, so I don't want to get into the engineering details more than necessary. Just for background, the ...
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How do grandfather clocks keep going?

How do grandfather clocks keep going? The pendulum is what makes the clock go. However, the pendulum will slow down due to friction. What energy source keeps the pendulum from eventually stopping?
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4answers
158 views

What is the speed of Newtonian gravity?

I already read this Phys.SE question but my question is different. I'm well aware that the effect of gravity in GR gets transmitted from point to point at the speed of light. But let's ignore GR for ...
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2answers
48 views

Gravity effect on moving bodies

If we imagine two suns of equal mass, and a small object in their combined center of gravity, which is not moving, it will stay there forever. If the object is displaced a little bit towards one of ...
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2answers
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How did Newton find out gravity is proportional to the product of two masses? [duplicate]

I am going to ask a really stupid question here. It is a very well known fact that gravity is inversely proportional to the distance squared between two masses. I understand how he arrived at this ...
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5answers
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Resolving General relativity and Newtonian mechanics to a computer [closed]

I know this is considered an old subject long ridiculed by many as the folly of layman. But I work in the field of computer simulation, specifically in producing fully functional 3D interactive ...
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2answers
82 views

Gravity - change with altitude

Does acceleration due to gravity, $g$, which is calculated by Newton's equation, decrease with altitude? Forgive the silly question.
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Why does Earth accelerate every object toward itself with acceleration of $9.8\, m/s^2$ [closed]

Why Earth accelerates objects due to gravity with $9.8\,\mathrm{m/s}^2$. How to demonstrate that?
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1answer
96 views

Solving the Three-body problem numerically

I want to create a program in $Mathematica$ that solves numerically the Three-body problem by Euler-Lagrange's equations. I was searching some methods to sucessfully do it. So I found a way to solve ...
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1. How is Newtonian calculations compatible with curved spacetime? and 2. multiple competing reference frames for gravity [duplicate]

Since spacetime is curved, and since the measurement of distance on a curve is along a geodesic, how is it that Newtonian (non-curved) physics can be successfully deployed to calculate distances, ...
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What would be the rate of acceleration from gravity in a hollow sphere?

Lets say the Earth is hollow and you are in the center of it (Same mass except all of it is on the outside like a beach ball) If you move slightly to one side now your distance is closer to that side ...
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19 views

Shell theorem using Gauss Law

Let me present you my problem: Two spherical shells with radius $R_1$ and $R_2$ ($R_1 < R_2$) and masses $M_1$, $M_2$ are concentric. Calculate the gravitational force $\vec{F_g}$ applied ...
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1answer
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How would change force of gravity? [closed]

How would change force of gravity, impacting some object, when this object is lifted on height $h = 3 \cdot R_3$. The right answer stated as ("decrease 16 times"). I want to know why.
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1answer
107 views

Which point in the graph does a parachute open?

The diagram represents speed-time for a sky diver. He falls freely from an aircraft then opens a parachute and later lands safely on the ground. At which point did the parachute fully open? ...
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1answer
65 views

Time to fall in a non-uniform gravitational field

In an uniform gravitational field the loss in potential energy (the work done) by gravity is given by $\text{-}mg\Delta h$ and the time to do so (assuming no friction and no initial velocity) is given ...
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1answer
60 views

How can I solve this differential eqution with IVP? [duplicate]

$$m\frac{d^2r}{dt^2}=-G\frac{Mm}{r^2}, \qquad r(0)=R ,\qquad \dot{r}=v_0>0$$ describes the free fall of an object of mass $m$. $r(t)$ is the distance of m to the center of the earth which is $R$ ...
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1answer
122 views

Minimum energy required to roll a cuboid through $90^\circ$ [closed]

I'm stuck on this textbook question about the minimum energy required to roll a cuboid through $90^\circ$ from an upright position to a horizontal position (see image). I believe the correct answer is ...
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1answer
59 views

Calculating pendulum rate variation due to change in force of gravity over arc of swing

Hi all and thank you in advance for any insight into this problem. I'm a journalist working on a story on precision pendulum clocks and specifically on the isochronism of pendulums. I note that the ...
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3answers
201 views

Weight distributions [duplicate]

If a man is standing on two weighing machines (scales), with one foot on each, Will both machines show equal weight or his weight will be distributed in two machines?
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1answer
223 views

Maximum range of projectile launched from an inclined plane [closed]

As we already know the max range if we launch it from any flat surface or from any height but I was wondering what will be maximum range if we launch it from inclined plane. I have made on figure of ...
2
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2answers
377 views

Why inverse square not inverse cube law? [duplicate]

So as I understand, the inverse-square law which shows up in a variety of physical laws (Newton's universal law of gravitation, Coulomb's law, etc.) is a mathematical consequence of point-like ...
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0answers
25 views

What would be the shape of a candle in a zero gravity environment? [duplicate]

What would be the exact shape of a burning candle if it is placed in a zero gravity environment...I am not able to determine the way the fire and the candle aligns.. Please help me out!
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3answers
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Why does it hurt more to fall from 10 stories, than 1?

$F=ma$. Falling from any distance, mass stays the same, and acceleration due to gravity stays the same. So, why does it hurt more, the longer you fall?
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Can adding weight to something make it tilt slower?

Let's say we have 2 sticks, both a meter long. We put both of them on the ground vertically. To the top of one of them we attach a weight. Then we tip both of them over and let them fall. Assume ...
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3answers
138 views

Since the gravitational force is only attractive, why does matter not just concentrate into a small sphere?

This doubt has been wandering in my head for a long time. The gravitational force is only attractive force not a repulsive force. Since gravitational force is only attractive force, why not the ...
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2answers
89 views

Gravitational potential difference

in my revision guide it defines gravitational potential difference as: The gravitational potential difference is work done in moving a unit mass. It then goes on to explain the gravitational ...
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What would happen if I were to fall into a massive hollow planet?

Imagine, if you will, there exists somewhere out there a supermassive planet. For some reason, this planet is only a shell of its former existence and all that is left is a crust of substantial size ...
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1answer
208 views

What does this sentence mean?

"The acceleration of free fall on the surface of the Earth is 6 times its value on the surface of the Moon." I interpreted it as: "The acceleration of free fall due to the Earth's ...
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1answer
47 views

How did the Moon survive next to the Earth since earth and Moon came into existence?

What mechanism(s) prevented the gravitational effect of the earth on the moon from shattering the moon when it was closer to the earth than the Roche Limit some 4.5 billion years ago?
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51 views

Is the acceleration of a soap bubble the standard value of gravitational acceleration?

Is the acceleration of a basic soap bubble the same as the standard value of gravitational acceleration 9.81 m/s^2 when it is dropping in a windless space? I have used the Newton's 2nd law to prove ...
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3answers
54 views

Gravitational field strength and potential different signs

In my revision guide the gravitational field strength is given as $g=GM/r^2$ whereas gravitational potential is $V=-GM/r$. Why does potential have a minus sign but field strength doesn't?
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1answer
190 views

Graph of electric potential

In my AP physics guide the graph for electric potential (for a radial field, i.e. point charge) and gravitational potential (for radial field, i.e. point mass) slightly differ from each other and I ...
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1answer
33 views

Pendulum at an angle

A pendulum has a period of $T$ when swinging from a string. The pendulum is now placed on a frictionless incline at a 30 degree angle. What is the new period of the pendulum?
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Why do planets moving around our Sun lead to how stars move around the centre of a spiral galaxy?

We know that the speed with which the planets go around our sun decreases as a function of the distance they are from the sun. Since stars are not planets, and presumably do not behave like planets, ...
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1answer
106 views

Force of Gravitational attraction between the ring and the sphere? [closed]

Let us say a uniform ring of mass m and radius 3a is kept above a sphere of mass M and radius 3a at a distance of 4a such that line joining the centres of ring and sphere is perpendicular to the plane ...
2
votes
1answer
90 views

Is there a fundamental relationship between Coulomb's law and Newton's Law of Gravitation? [duplicate]

It seems like the two equations are identical indicates that there is something more going on that unites them both, maybe in a cool way or something. Why are these two laws so similar?
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What is third cosmic velocity?

I have been studying Gravitation chapter and there I found one term : Third cosmic velocity which is also known as interstellar speed. So what is it ? What it really tells about? I tried to gather ...
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4answers
113 views

How to measure the mass of Earth?

I was wondering how you can measure the mass of Earth. From what I find on the internet, people are using Newton's Laws. But how can you do that ? Newton's Laws are assumed to work because you know a ...
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1answer
42 views

How are the theoretical properties of a gravity train linked to orbital properties?

Whilst perusing a question on WorldBuilding, a link was given to an article about Gravity Trains. Some of the answers on the question, and the Wikipedia article, state a travel time of 42 minutes ...