New answers tagged newtonian-gravity
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Gravitational potential energy in Escape Velocity
The gravitational force acting on the body is $$\mathbf F_g = -\frac{GMm\mathbf{\hat r}}{r^2}$$
If it is the net force, we can apply the Newtonian second law:
$$-\frac{GMm\mathbf{\hat r}}{r^2} = m\...
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Gravitational potential energy in Escape Velocity
The long answer is that the equation you provided (force times displacement, $E=\mathbf{F}\cdot\boldsymbol{\Delta}\mathbf{r}$) is for a specific type of energy, but this energy is work (not potential ...
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Which force provides the centripetal acceleration that makes objects on earth's surface rotate about Earth's axis of rotation?
cbr paradox:
...water level is not horizontal everywhere, because if it were then the Earth would either be a stationary sphere or flat...
The rise of the water is (on average and at 45 degrees ...
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Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?
And yet there are a zillion celestial objects perfectly orbit each other
This is survivorship bias. Based on our current model of how we think planets form, there were many orders of magnitude ...
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Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?
Btw, here's an expertly drawn diagram that took 1000 hours in MS Paint to show things visually.
None of your three pictures really illustrates the actual physical scenario very well. (OK, picture B ...
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Question on Gravity (Ring and Sphere) from JEE Mains 2021
The gravitational force from the sphere on any "chunk" $\Delta m$ of the ring is indeed $G M \Delta m / (3 R)^2$ (note the parentheses). However, this does not mean that the net force on ...
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Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?
Partly it's about how galaxies form (see another excellent answer about that).
But do also consider that you're seeing the survivor bias of 13.8 billion years. If they weren't in a stable orbit, the ...
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Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?
they can either miss each other and fly apart (if the velocity is enough and there's not enough gravitational attraction between them), or they can be attracted enough to each other that they ...
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Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?
chausies asked: "Why are there so many objects perfectly orbiting each other?"
Apart from the fact that most orbits are not perfectly circular but more or less elliptical: if two objects ...
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Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?
Your intuition that two isolated objects approaching each other and not already in a closed orbit will either collide or will fly apart again is substantially correct. If the objects are not already ...
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Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?
At first glance it may seem this way, but conservation of angular momentum sort of acts as a "restoring pseudoforce" to make orbits more likely.
If one object is traveling towards another ...
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Does this question require any calculus to solve?
The multiple-choice answers are an editing mistake. No one measures distances in joules.
You suggest in a comment that perhaps the intention is to integrate over the motion to find work done. But you ...
rob♦
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Total energy of a rocket launch
For a chemical rocket, the energy source is chemical energy. This energy becomes thermal and kinetic energy of the ejected propellant and of the rocket itself. As the rocket moves upward from the pad, ...
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Total energy of a rocket launch
It then launches, and both KE and PE start to increase. How does this obey conservation of energy?
You forgot thermal energy and chemical potential energy, etc. Thermal energy also increases, but ...
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Gravitational Potential Energy irony
It is because the work done here considered is external work and gravity is pulling towards earth while we are applying approximately same force opposing it to cause opposite displacement that bring ...
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Observation of the effect of gravity on the motion of antimatter
Usually these error estimates are "one sigma" error bars, which is roughly the same thing as a 68% confidence limit. If you have an ensemble of data with $1\sigma$ error bars, you expect ...
rob♦
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Why does gravity cause objects to pull other objects with constant acceleration and not constant force?
Assume this situation:
A mass $~m_1~,m_2~$ both are at the start position $~R+h_0~$ and both are falling to the surface of the earth, there isn't any air drag.
The equation of motion for $~m_1~$
$$...
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Why does gravity cause objects to pull other objects with constant acceleration and not constant force?
Every single atom pulls every other atom with the same force (not exactly but good enough). If you double the weight of one body and triple the weight of the other, then you have twice as many atoms ...
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Why does gravity cause objects to pull other objects with constant acceleration and not constant force?
Imagine that you have an object of mass $M$ attracted to the earth, with the force acting on the object being $F$. You are asking if we can prove intuitively why $F$ should be proportional to $M$ - i....
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Why does gravity cause objects to pull other objects with constant acceleration and not constant force?
Why does gravity cause objects to pull other objects with constant acceleration and not constant force ?
Science generally doesn't give very satisfactory answer to "why is the universe the way ...
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Why does gravity cause objects to pull other objects with constant acceleration and not constant force?
In general objects don't experience a constant acceleration due to gravity. But near the surface of the Earth they nearly do.
The gravitational force acting on a pair of objects depends on their ...
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Why does gravity cause objects to pull other objects with constant acceleration and not constant force?
I think gravity may not be a force per se. If it were a force then it could be expressed as a quanta. Unfortunately, Einstein's theories cannot be reconciled with quantum theory and quantum theory is ...
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Sign of force for assumed $mgy$ gravity
If you assume force is $mgy$:
After reading OP's comments, it seems that OP just wants to understand how to solve a problem where the force is proportional to the displacement.
The main problem the ...
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How do i calculate a projectile range accounting for a planet's curvature?
I tried to figure this too.
I had this hypothesis:
if rocket is launched to some angle instead of straight up, Apoapsis should be more high because planet has curvature.
I tried to calculate how high ...
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Time taken for object in space to fall to earth
I think that the equation $T=\frac{\pi}{2} * \sqrt(\frac{R^3}{2Gm})$ is incorrect equation.
If we tested the equation with a height of $h=100m$ away from the surface of earth. It could be good to use ...
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Escape velocity work done problem
to provide velocity to send to infinite distance from gravitational pull of earth so for that we have to apply external force
This is called an “initial velocity”. The problem begins at the “initial ...
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Can mass be negative?
We don't have any physical evidence for negative masses. In general relativity there are some interesting mathematical solutions, such as "wormholes," that become stable if you have access ...
rob♦
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What is the smallest known gravitationally bound system?
Some asteroids or comets are not solid bodies. Instead they are collections of rubble, weakly held together by gravity. The smallest such body is probably the system you are thinking of.
JPL's Small-...
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How much kinetic energy would a star in a galaxy have if it fell to the center?
A fair answer can be achieved using Newtonian physics. Assuming that the star was stationary prior to infall (as you want), we would need to find its potential energy. If it falls to the center, then ...
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Why do gravity and electricity sometimes obey inverse square laws over the same distance scale?
The modern point of view is that we should understand field theories as effective field theories, or low energy approximations of more complete theories. Because of the uncertainty principle, "...
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Why do gravity and electricity sometimes obey inverse square laws over the same distance scale?
To get an idea as to why it helps to think about field lines. If you imagine a sphere enclosing an electric charge or mass then the number of field lines coming into or out of the sphere depends only ...
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Find the acceleration of a block sliding down on an accelerating inclined place
The acceleration $\mathbf a$ is referred in the frame of the inclined plane.
\begin{align}
\mathbf b &= b\cos \theta \, \mathbf i+b\sin \theta \, \mathbf j \\
\mathbf g &= g\sin \theta \, \...
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Is there a way to express the collisionless boltzmann equation in terms of positions, velocities, times, without the distribution function?
I think what you're looking for is called Newton's second law. You know the force acting on a single particle, you calculate its acceleration, and you follow this particle in its motion through space ...
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Is there a way to express the collisionless boltzmann equation in terms of positions, velocities, times, without the distribution function?
A single particle will just follow Newton's force equation, using the acceleration as $a=F/m$, where $F$ is the prescribed force on particles. The Boltzmann equation is built from the assumption that ...
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How much kinetic energy would a star in a galaxy have if it fell to the center?
The rotation curve $v ( r )$ for the galaxy will give the centripetal force experienced at any radial position $F = \frac{mv^2}{r}$. The kinetic energy in this scenario would be $ \frac{mV^2}{2} = KE =...
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Why was Heaviside perplexed by this property of the gravitational potential?
There is an article about this subject on the website 'mathpages'. The article is titled Why Maxwell couldn't explain gravity
Heaviside's thinking was strongly influenced by Maxwell's work.
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Which of Newton's shell theorems applies to a galaxy?
Livid asked: "Which of Newton's shell theorems applies to a galaxy?"
For a spiral galaxy none of these theorems apply, since it is not spherical but rather approximated by a disk with a ...
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