Questions tagged [newtonian-gravity]
This tag is for questions regarding the Newtonian model of gravity in which the force between two objects is given by $~GMm/r^2~.$ It is a natural phenomenon by which all things with mass or energy – including planets, stars, galaxies, and even light – attract one another. On Earth, gravity gives weight to physical objects, and the Moon's gravity causes the ocean tides.
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While lifting an object shouldn't a man apply a force equal to gravity but negative one?
We know that, if we lift an object from the ground we have to apply equal force to $m g$. But while we are calculating the workdone for the person, shouldn't we take the $F$ in negative? As we are ...
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Can 3 objects with same mass dropped from 10,000ft land in the same region/area together? [closed]
I mean specifically VERY close together, like in the same spot next to each other? And specifically, for example, objects such as 3 separate elastic band-bound bundles of €20 bills amounting to €2,000 ...
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Multidimensional space and Newton's inverse square law deviation [duplicate]
Many times I have heard the physicist Michio Kaku saying that the deviation on Newton's inverse law could demonstrate the existence of multidimensional space, which could support one of the aspect of ...
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What is the difference between GPE and gravitational self energy in GR?
What is the difference between gravitational potential energy and gravitational self energy in General Relativity? Are they both the same in Newtonian gravity?
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How does gravitational potential energy work in a very large distance?
I have a question that I made up when I was in high school in first year when we started physics and potential energy and something like that. The question goes like this:
Imagine the universe has ...
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Conserved Quantities in the Two-Body Problem
I'm having trouble matching the number of conserved quantities in the two-body problem with the number of differential equations.
We know that, considering positions and velocities in the two-body ...
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Two balls are dropped from the same height. Ball A is metallic and B, made up of an insulating material. Which of them touches ground first? [closed]
General motion under gravity states that both of them reach the ground simultaneously. But here, ball B reaches first. I searched for the solution but couldn't find any. Does it have anything to do ...
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Gravitational potential energy of a galaxy
How can the total gravitational potential energy of a galaxy be calculated?
Lets assume for simplicity that the entire galaxy follows an exponential mass density function for an infinitely small ...
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Nuclear binding energy and gravitation
A nucleus $A$ can be split into two smaller nuclei $B$ and $C$. It is well known that the sum of the masses of $B$ and $C$ will not equal the mass of $A$ due to the nuclear binding energy and the ...
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Newton's 2nd law and gravitational law [duplicate]
I am studying the Newton's Law's of Motion, and really confused about one thing.
I know that bodies of very small mass get attracted to our earth due to a force it exerts, due to its huge mass.
So ...
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Angular velocity in planetary motion
Torque about centre of sun is zero.
$$T=Ia$$
So angular acceleration is zero too, so angular velocity should remain constant.
However it is not the case. Please tell where I went wrong.
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What are the conditions that produce various shapes in 2D motion?
I have read that projectile motion is parabolic in nature. I know that the equation of projectile motion represents a parabola. But when do we get a parabolic curve? Does it happen when there is ...
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Two-Body Problem as a function of $t$
I'm writing an orbital simulator program and I'm struggling to apply the two-body problem.
To simulate it properly I need values for the $x$, $y$, and $z$ coordinates for both bodies. Ideally, these ...
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Do all bodies in a 3-body system orbit their center of mass with respect to each of the other bodies?
Scenario
Consider an empty universe with just the Earth, Moon and the Sun. The Earth and the Sun will rotate about their center of mass, which is inside the Sun. The Earth and the Moon will orbit ...
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Question on Coulomb force compared to Newton gravity
I have recently started reading Volume 1 of The Feynman Lectures on Physics. I am going through Chapter 2, Section 2-2 Physics before 1920.
I came across this particular discussion within section 2-2:
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Additional term in energy-stress tensor for classical gravity
Consider a flat Minkowski space. Given is the field $\phi = \phi(t,\vec{x})$ and the Lagrangian with minimal coupling to matter $$L(\phi, \partial_\mu \phi) = \frac{1}{8\pi G} \partial_\mu \phi \...
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Is there any effect of gravity in a vertical nonlinear spring? [closed]
I know that for a linear vertical spring, the governing equation of motion written in the presence of gravity is the same as the one written in the absence of gravity. We can either undergo a ...
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Is this already an established functional relationship or have I created hodgepodge?
Last winter I started toying with the galaxy gravitational rotation curve graphs. I started modifying the exponent of $r$ that in effect change the $1/r^2$ law and therefore correct the mismatch, ...
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Would it be possible for a cylindrical magnet suspended vertically down from a hanging magnet to levitate in static equilibrium?
Let's assume that a cylindrical magnet is clamped by an horizontal arm extending out of the wall. The top of the magnet is its north pole and the smooth face facing down is its south pole. If I bring ...
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Can Gravity alone produce a simple Hydrogen or Helium atom?
Imagine there is no EM or Nuclear Force, and Gravity is the only force.
Can gravity alone produce an atomic structure similar to a basic atom?
In this scenario, the nucleus is just a single particle. ...
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If you pick an object from ground and place it at bookshelf.. it has gained potential energy
If you pick an object from ground and place it at bookshelf.. it has gained potential energy but no change in kinetic energy.. does it violate law of conservation of energy
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Conserved Quantities in Kepler Problem?
In our classical mechanics class, professor said that Kepler's problem is a kind of Integrable System such that the number of conserved quantities would be equal to the number of degrees of freedom. ...
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How does gravity do work to a horizontal projectile?
Suppose a ball is moving in a horizontal projection with some velocity $u_0$ in the positive $x$ direction. Here we see that although gravity is perpendicular to the velocity vector, it changes the ...
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Atoms in the cavendish torsion balance
Some people who try to deny the Cavendish Experiment say that the masses attract each other because of the atoms, not gravity. Doesn't an atom have a null electric field by nature? Is there any other ...
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Electric potential difference due to gravity [duplicate]
A colleague asked me an interesting question: If you have a copper bar, let's say 1 meter long, and stand it upright: Is there an electrical potential difference between top and bottom due to gravity?
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Air resistance in the Cavendish Experiment
Would air resistance be an issue in the Cavendish experiment or are the velocities so low as to be irrelevant? Could it cause the experiment to fail?
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Will a very long space ship orbiting the Earth appear to have gravity to someone inside?
My friends and I have several disagreements about this scenario:
Imagine a rigid cylinder that is the length of the diameter of the earth. At either end of this cylinder is a capsule with a person ...
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How a force that is always perpendicular to velocity can change the kinetic energy when another force is acting oppposite to velocity? [closed]
When a satellite is revolving around a planet with an orbital velocity in presence of air resistance, the satellite's Kinetic Energy keeps on increasing as it falls down. The resistive force is trying ...
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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$$ since we are assuming ...
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How to add kinetic energy to gravitational energy to obtain total energy?
Cambridge Pre-U 9792/03/M/J/22
Examination question: What is the total energy E of the binary star system?
Given: The kinetic energy of star X is $E_x = \frac {2GM^2}{9D}$
Working:
$E_Y = \frac{GM^2}{...
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In one formula of orbital velocity for circular orbit it has inverse relation with radius while in critical velocity relation it has direct. Why?
In one formula of orbital velocity for circular orbit it has inverse relation with radius
$$v=\sqrt{\frac{GM}{r}}$$
while in critical velocity relation it has direct
$$v=\sqrt{gr}$$
Why?
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What is the gravity in the center of Earth?
Let's suppose the earth is perfect sphere and let's ignore its rotation and movement.
What would happen if i would be in the center of the earth? Would the gravity be zero in any direction so i wouldn'...
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Reason of object not leaving earth surface
The earth rotates around the sun at speed of approximately $18.5$ miles per second. And the escape velocity of earth is $6.96$ miles per second. So the speed of rotation is greater than the escape ...
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Will a man acquire orbit if we suppose Earth is rotating fast enough?
if we consider that the rotation of earth is mush faster (30000km/h), so if a man standing on earth jumps 1 meter above will it acquire orbit if we ignore atmospheric friction
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What is the total energy of newtonian polytrope stars of index $n > 5$?
In classical newtonian theory, we could find a general expression for the gravitational potential energy of a polytrope sphere (of pressure $p(\rho) = \kappa \rho^{\gamma}$, where $\gamma = 1 + \frac{...
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Relationship between height and mass?
Objects with different masses are placeed on the horizontal surface of a table. The objects are then raised to different heights above the tabel. The gain in gravitational potential energy of each ...
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An extra term in the calculation of Newton's gravity energy density [duplicate]
The lagrangian density of a newtonian gravity is:
$$\mathcal{L} = -\rho \Phi - (\nabla \Phi)^2$$
up to certain constants. I made analogies with electrostatics and I believe that the energy density of ...
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Interpretation of gravitational waves
A wave has peaks and valleys. I can think of a sine wave as a wave with peaks and valleys.
Now, if gravity is a wave, can we say that gravity would have peaks and valleys, with the valley becoming ...
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Gravitational binding energy of a part of system
I want to calculate the gravitational binding energy of a small central cube (length $l$), which is part of a much larger cube (length L). I have the mass and gravitational potential distribution ...
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What is the gravitational field intensity of a uniformly distributed mass content in Newtonian gravity?
In an infinite universe composed of single point masses which can be simplified as a uniformly distributed mass density, what is the equation for the gravitational field intensity in Newtonian gravity?...
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Can mechanical waves exist in zero gravity?
Just got out of a test and there was this question asking of true/false:
“A fluid presents pressure variation only when subjected to a gravitational field”
To which the alleged correct answer was “...
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Conservation of Angular Momentum in Elliptical Orbit: simple yet confusing [closed]
Problem
A satellite orbit is to change from elliptical to circular with radius $2 R$. The satellite is at point $A$ on the elliptical orbit as shown in the figure. Determine the speed of the ...
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In orbital mechanics why is the angular momentum $\bf{h}$ constant?
In the context of an object moving under the influence of gravity, in Bate, Mueller, White it says, sect. 1.4.2
The expression $\bf{r} \times \bf{v}$ which must be a constant of the motion is simply ...
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How to calculate the period of non-circular orbits?
How to calculate the period of non-circular orbits?
By conservation of mechanical energy:
$$
E = -\frac{GMm}{r} + \frac{1}{2}\mu \left ( \dot{r}^2 + r^2 \dot{\theta}^2 \right )
$$
By the conservation ...
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How to derive the period of non-circular orbits? [closed]
By conservation of mechanical energy:
$$
E(r_0)=-\frac{GMm}{r_0}+\frac{1}{2}\mu \left (\dot{r_0}^2+r_0^2 \omega_0^2 \right)
$$
where $r_0 =r_{max}$. Because our body is located at the apoapsis: $v_r = ...
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How is when an object moves gravity not effect it ? As Einstein sais?
Experiment:
*a water bottle with a hole . Water is falling from the hole when the bottle is in rest . When the bottle is released and falls , water stops falling as gravity is not doing effect on it . ...
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What is the significance of a reference point in calculating the potential?
The gravitational potential is given as $$U(r)=-\frac{GMm}{R}$$ where $G$ is the universal gravitational constant $M$ is the mass of the earth and $m$ is the mass of an arbitrary object and $R$ is the ...
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Will the moon ever proceed to lose its orbit and hit the earth?
Assume that the moon it orbiting the earth in a circular trajectory.
It will experience an acceleration directed towards the centre of the earth given by $\frac{GM}{R^2}$ where $G$ is the universal ...
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Is there an equation that is quick to use that calculates gravity around black holes?
Is there an equation the can calculate gravity around black holes but is less time consuming than EFE? I want to find an equation that is simpler/faster than Einstein's Field Equations but can still ...
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So I've found out heavier objects technically do fall faster? [duplicate]
Given the Earth's mass to be $M_E$, I know that $F_G = -\frac{GM_Em}{d^2}$, so the gravitation acceleration of a mass towards Earth is $g = -\frac{GM_E}{d^2}$. But what about the force exerted by the ...
