Questions tagged [newtonian-gravity]

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

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Why does the gravitational field for certain configurations, at certain points in space, diverge to infinity? [duplicate]

I recently came across this problem, in David Morin's weekly problem set. The solution to which I figured, as explained here. But I also came across the solution explained in this report. Here the ...
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Black Hole Coin curve

I've seen a toy at my local pharmacy called The Black Hole that lets you insert a quarter into a vertical slot. The quarter starts rolling around a curved funnel's circumference and slowly winds its ...
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Is there a link between $G$ and speed of light? [closed]

I tried to resolve $G$ from natural units (like Planck), and found that $$ G = (K \times c / r_0)^3 $$ where $ G = 6.67430 \times 10^{-11} $ is gravitational constant, $ K = 1.66053906660 \times ...
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Planetary motion considering natural satellite

Using Kepler's laws of gravitation we can determine the time period of a planet revolving around the sun. However, this excludes the gravitational effect due to satelite(s) orbiting around the planet. ...
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Does Earth's Gravitational pull increase with time?

Gravitational field depends on mass ($g = \frac{GM}{r^2}$) and every year many outside cosmic objects like asteroids or tiny object are hitting earth. So I think may be in a very microscopic amount ...
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The physics behind Hohmann Transfer Orbits

I was recently reading about Hohmann transfer orbits from the MIT courseware on orbital transfer (source). I have two questions. How did they arrive at the equations for $v_{\pi}$ and $v_{\alpha}$?...
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Proof for elliptical orbits [closed]

Its mentioned in several books that a satellite launched with a velocity less than the escape velocity and other than the critical velocity will follow an elliptical orbit. However I can't find a ...
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MOMENTUM TRANSFER [closed]

2) Oil with a viscosity of 25 cP and SG(specific gravity) = 0.78 is contained in a large open tank. A vertical tube, made of commercial steel, with a 1 in. ID and a length of 6 ft, is attached to ...
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Why don't the satiltes fall into the earth? [duplicate]

Still, I don't understand how come the satellites won't fall into earth. I know the general explanation to this question is that the satellite's horizontal velocity is too fast that makes the gravity ...
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Is the gravitational force for an object on the surface of earth always pointed to the center?

I thought it would be so because the mass inside the earth would attract us however they would be at a larger distance than masses on the surface of the earth. For example, consider having a tall ...
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Why does the property of a projectile is different from a parabola (with the opening downward) represented by a quadratic equation?

The property of a projectile make me think about those sine and cosine graphs I had learned in trigonometry class, which the distance between every two points on that parabola is the same but the ...
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How can we use Kepler's Laws of Planetary Motion to derive a general formula for the orbital velocity of a planet? [closed]

I am curious to know how Kepler's Laws can be used to figure out the velocity of a planet, in relation to its mass, radius, or the force of gravity exerted on that planet.
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Is this expression for the energy of a three-body system correct assuming Newtonian mechanics? [duplicate]

In the (currently unanswered) Math SE question Can there be an energetically unbounded three-body orbit where escape is impossible due to conservation of angular momentum? I've I'd written†: The ...
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Could an asteroid capture an object and bring it into orbit as the asteroid moves through space?

I'm a scifi writer and have very limited knowledge of astrophysics and I'm working on a story where my character lands on a moving asteroid. In the original draft of the story, my character is on an ...
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Relationship between gravitational field strength, mass, density and altitude [closed]

Explain why both mass and density affect the gravitational field strength at the surface of any celestial body. Explain why the gravitational field strength does not depend on the density of the ...
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How are gravitational forces compensated? [closed]

I would like to go through three scenarios of forces and their exact "anchoring": there are two ice skaters A and B, standing still on the ring. They touch each other with the palms and one of them ...
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Does Acceleration due to Gravity take into consideration the centrifugal acceleration due to Earth's spin?

Is the gravitational acceleration we consider only the attraction due to the Earth's gravity or is it that of gravity plus the attraction due to Earth spinning? We know that earth produces an ...
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Doubt with gravitation [duplicate]

I am a math student and I am taking my first physics course of Mechanics. But I don't know the difference between the $w=mg$ force and $F=G\cfrac{m_1 m_2}{r^2}$ (why we don't use the first one when ...
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If space is expanding, what is the effect on $1/r^2$?

Space is expanding, and this effect can be only detected at large scales, on the scale of galaxies and larger. If space is expanding, the expression $1/r^2$ for the law of gravity will be modified. ...
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Average quantity over Keplerian orbit

I have been working through some lecture notes and am quite confused on something. I am trying to understand how to average a quantity over an orbit (Keplerian) but I am struggling to get a clear idea ...
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Is weight = Gravitational Force - Centripetal force?

Is weight ≠ gravitational force, for an object on the Earth’s surface? Why is this? Is it because part of the gravitational force acts as a centripetal force? Does the normal contact force not nullify ...
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Why is Principle of superposition not oftenly used for gravitational potential?

We talk a lot about this principle for electric potential at point by many charges but not for gravitational potential by other masses around it, why?
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where do the gases such as hydrogen and helium end up after leaving the earths atmosphere?

I've heard that gases like hydrogen and helium leak out of the earth's gravity a little by little. but where are they going? where do they end up after leaving earth's pull? would the sun pull them ...
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How do I obtain the trajectory of a particle in the plane using Newton's law of gravitation? [closed]

Problem: Suppose we have a fixed planet $A$ exerting gravitational force and a particle $B$: I want to obtain the function that gives the trajectory of $B$ to $A$. If $B$ has no velocity and no ...
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What is the difference between the center of mass and center of gravity? [duplicate]

What is the difference between the center of mass and center of gravity of a rigid body? In which cases are they the same point and in which cases are they different points?
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Why is the Force of Gravitational Attraction between two “Extended” bodies proportional to the product of their masses?

Newton’s Law Of gravitation states that force of attraction between two point masses is proportional to the product of the masses and inversely proportional to the square of the distance between them. ...
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Why in the formula to get the escape velocity $v_f$ is $0$?

The formula to get the escape velocity is: $$K_i + U_i = K + U$$ $$\frac{1}{2}mv^2_i-G\frac{mM}{R^2} = \frac{1}{2}mv^2-G\frac{mM}{r_\infty}$$ $$\frac{1}{2}mv^2_i-G\frac{mM}{R^2} = 0$$ My question is: ...
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Is it possible to have zero gravity points on earth by changing the angular speed of rotation of earth?

Let F(gravitation) be force due to gravity , and F(pseudo) be the pseudo force in earth's frame of reference. It comes to me that those two forces are not parallel (see the image) and will never ...
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How did $4$-distance in General Relativity become displacement in Newtonian Gravity?

In general relativity the christoffel symbols 'pop' out of the metric $g^{\mu \nu} dx_\mu dx_\nu$. When $g^{\mu \nu} dx_\mu dx_\nu$ is integrated it is a measure of distance between the $2$ points. ...
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Is 1 Joule the work done to lift ~100g through a distance of 1m?

I am seeing many videos saying that 1 Joule is the work done to lift ~100g through a distance of 1m (like this one https://youtu.be/BYpZSdSEk4A?t=348). The idea is that 100g has a gravitational force ...
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How we calculate potential energy in best accuracy?

This question may be a bit ridiciolus but let me explain. I'm not talking about the formula, I am talking about, what is the best accuracy of calculating the potential energy. For example, let I ...
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How high can you jump (at the corner) on Cube-Earth?

I have read this question: Is the force of gravity always directed towards the center of mass? And G. Smith's answer lists a site where they specifically talk about this case mathematically. https:/...
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Question about Newton's Shell Theorem

This drawing shows the Newton's Shell Theorem about the situation that the point mass $M_1$ is outside the spherical shell $M_{\text{shell}}$. My teacher showed that the differential element of the ...
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Trajectory due to gravitational forces

The trajectory of a body moving under the gravitational influence of a second fixed body is a conic section. Can this statement be proved without the use of calculus?
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Can I cancel out the gravitational force when calculating the gravitational constant? [closed]

Basically, this is what i’m doing: $$F = m_1a$$ $$F = \frac{Gm_1m_2}{r^2}$$ where: $F$: gravitational force $m_1$: mass of the earth $m_2$: mass of object dropped $a$: gravitational ...
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How does the Equivalence principle explain “what goes up must come down”?

Apologies if this is a dumb question, I am mostly self-taught when it comes to physics. I recently came across this video by PBS Space Time (Is Gravity an Illusion?) which talks about the Equivalence ...
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For an object sliding down a frictionless sphere, what happens at the moment it loses contact with the sphere?

The following diagram shows the situation described in the question: I learned that at the moment the object loses contact with the sphere, there won't be a normal force acting on the object. However,...
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What is wrong with this calculation of work done by an agent bringing a unit mass from infinity into a gravitational field? [duplicate]

Let us assume that a gravitational field is created by a mass $M$. An agent is bringing a unit mass from $\infty$ to distance $r < \infty$, both measured from mass $M$. The agent is always forcing ...
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Is there an effect analogous to the slowing down of massive particles in Newtonian cosmology?

We know that massive particles slow down by $a^{-1}$ in the Robertson-Walker metric , where $a$ is the scaling factor. If the particle velocity is non-relativistic, can we understand this slowing ...
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Is the force of gravity always directed towards the center of mass?

This is a pretty basic question, but I haven't had to think about orbital mechanics since high school. So just to check - suppose a [classical] system of two massive objects in a vacuum. If the ...
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Why is the gravitational potential energy defined as negative? [duplicate]

It is said that since work is done by the gravitational potential itself , so at a finite distance the gravitational potential energy of the body is negative. Could someone explain why?
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Question about acceleration equations that can be used for a single object

Can the centripetal acceleration equation $a=\frac{v^2}r$ and the acceleration due to gravity equation $a=\frac{Gm}{r^2}$ be used interchangeably to find the acceleration of a single object?
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Analytical expressions for acceleration due to zonal harmonics of a gravitational field?

Wikipedia's Geopotential_model; The deviations of Earth's gravitational field from that of a homogeneous sphere discusses the expansion of the potential in spherical harmonics. The first few zonal ...
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Rigorous Limit Derivation of Kepler's Second Law

I'm wondering if anyone can provide me with a more rigorous derivation of Kepler's second law. I looked this up online and couldn't find anything more rigorous than the usual. I'm reading Taylor's ...
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Derive Gravitational law [duplicate]

How can I derive Newton's gravitational law? $$F=G\frac{m_1 m_2}{r^2}$$ Is it impossible to derive? Did Newton get this just by obervations?
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Mass is affecting final velocity down ramp

I have been doing an experiment where 2 different skateboard frames (like a grind) slide down a metal ramp (1.5m) and the final velocity is calculated by video analysis. I would compare this to the ...
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Why does the mass of small objects not cause them to “pull” Earth towards them as slightly different speeds, as they fall to Earth? [duplicate]

Debate over dinner: we read on Wikipedia that objects fall at the same speed towards Earth regardless of mass. Then we remember seeing on TV ages ago an astronaut dropping a feather and bowling ball ...
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Regarding the objects in free fall in the ISS

There are lots of information about this topic, but I'm still greatly confused about something: Astronauts in the ISS are in free fall all the time because they have only gravity acting on them, but ...
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Gravity force inside the Earth

It is a well known exercise on classical Newton's gravity that assuming that the Earth has an ideal round shape to compute its gravity force at the given distance from its center. (Answer: it is equal ...
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What determines if an object will stay in a planet's orbit? [duplicate]

Say you threw an object 10 AU from a planet at a certain speed, would this object stay orbiting around the planet or would it shoot off into space? And does it depend of the speed the object when it ...

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