# 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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### Computing gravitational acceleration with General Relativity [duplicate]

As seen here, gravitational acceleration as a Newtonian concept can be considered in General Relativity as an artifact of the selected frame of reference for measurements. But can one compute the same ...
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### In fluids, what is the difference between the two forces in the formula $F=pA$ and $F=\rho Vg$?

I was doing a question on fluids which is: A living room has floor dimensions of $3.5 m$ and $4.2 m$ and a height of $2.4 m$. What does the air in the room weigh when the air pressure is $1.0 atm$?...
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### Theoretically, if you could attach a 1 meter string with a weight on the end to the exact center of the earth what would it do? [closed]

Would the mass of the weight keep moving towards the center but overshoot and repeat the process?
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### What is the reason for Moon and satellite in free fall condition?

I am a high school student. I read in my book that moon and satellite are in free fall condition with Earth. I asked my teachers about this, but I'm not able to understand. Can anyone explain to me ...
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### An error in a physics documentary?

I was watching The Amazing World Of Gravity (Full Physics Documentary) | Spark on Youtube, and I didn't quite understand a certain part. From 5:00 to 9:00, Professor Jim Al-Khalili was recreating ...
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I am trying to understand why the change in $E_{\mathrm{total}}$ of system BS is positive. Shouldn't it be the same since no energy is lost or gained? Also, can anyone explain how $\Delta U_g < \... 2answers 1k views ### Why is the distribution of dark matter in a Galaxy different from the distribution of normal matter? The dynamics of a galaxy are driven by gravity. And dark matter experiences the same gravitational forces as normal matter. The effects of other forces are very small in comparison. So why is the ... 0answers 46 views ### Does all objects really fall with the same acceleration? [duplicate] I know that acceleration due to gravity is independent of mass : $$a = \frac{F}{m} = G\frac{M}{r^2}$$ Meaning that a hammer and a feather fall with the same acceleration on the moon. I am confused, ... 4answers 143 views ### Why gravitational mass and inertial mass being same was a problem before Einstein solved it? Why is it so that Einstein is credited with telling us the reason for the equivalence of inertial and gravitational mass of an object? Did Newton ever make a distinction between the two masses? What ... 1answer 91 views ### **Mathematical Derivation** of the fact that all planets will orbit on the same plane There is some discussion about this Here. If an isolated system of particles under gravitational force is allowed to decrease its energy by means such as inelastic collision, then eventually all ... 2answers 64 views ### How does the Earth remain in its shape? I know only stars do nuclear fusion to keeps its shape from gravity. Then what about the Earth? Earth doesn't do nuclear fusion. How does the Earth keep its shape even though the gravity keeps pushing ... 1answer 142 views ### Will extracting power from ocean tides affect the moon's orbit in the LONG run? Conservation of energy says that any energy extracted from our ocean's tides would have to come from somewhere. Since these tides are a gravitational effect due to the moon, it would seem that the ... 1answer 68 views ### How to integrate acceleration due to gravity with height? [duplicate] If I project a body at a very large velocity such that it reaches a height h which is comparable to Earth's radius, then how to derive an equation for 'h' in terms of initial velocity 'u' and other ... 2answers 56 views ### How does the gravitational acceleration on a surface of planet change, if its radius shrinks while retaining the same mass? [closed] If the radius of the earth were to shrink by$1$% while its mass remained the same, then how would the acceleration due to gravity on the earth's surface increase by$2$%? 0answers 11 views ### Acceleration closed formula in strong gravitational field [duplicate] We know that acceleration of a falling body relative to earth is G*M_earth/(R_earth)^2 What would the acceleration formula if the earth's mass is same as sun's mass but with same earth's radius? Is ... 2answers 52 views ### Do planets in elliptical orbits exhibit constant magnitudes of acceleration in their orbits? I'm trying to reason through a problem. Consider Jupiter, which orbits the sun in an elliptical path. Is the magnitude of its acceleration constant throughout its orbit? My reasoning leads me to ... 0answers 40 views ### Why are so few inclined circumbinary planets known? For a research project I'm studying the orbits of circumbinary planets, most of these planets orbits are coplanar. However I was wondering if orbits with a high inclination could be stable. I made a ... 2answers 110 views ### Why does Friction act Parallel to the Surface (Microscopic Level)? If we assume an object (blue layer) sliding towards the right across a surface (black layer). According to Newton's 3rd Law, the frictional force would act to the left (resisting the object's relative ... 2answers 41 views ### How does the orbital radius affects the orbital velocity I have a question says that "If the orbital radius of a satellite increase four times the orbital velocity will be ..." and the answer is that the velocity will be doubled !! We studied that orbital ... 3answers 51 views ### Sphere and Bar freefall [closed] Question The problem consists of a bar of weight$W$to which a sphere of also of weight$W$is fitted at one end. The conbination is released from rest, with the bar horizontal. How will the ... 0answers 45 views ### Newton vs. Einstein in universe evolution description The equation for the universe evolution in the presence of a perfect homogeneous fluid, namely $$\dot{R}^2+k=\frac{8\pi G}{3}\rho R^2$$ can be obtained by solving Einstein equation with some effort. ... 1answer 103 views ### Is there a physical observable with the same units as$c/G$? Dividing the speed of light$c$by the gravitational constant$G$yields the dimension mass*time/area or mass/(length * speed) Is there a physical quantity used in textbooks with this dimension? I ... 5answers 8k views ### Is floating in space similar to falling under gravity? In the case there is no air and your eye are closed, then does falling from the sky under gravity have the same feeling as floating in space? Can our body feel that we are accelerating without the ... 2answers 41 views ### Increasing Mass VS Increasing Force when pushing a Box [closed] If we assume g=10m/s^2 & negligible friction The force needed to accelerate that box by 5m/s^2 would be 500N. This is a very basic one. The confusion came when an force of 250N (the force a 25kg ... 7answers 6k views ### Why doesn't the Earth's acceleration towards the Moon accumulate to create noticeable motion of the earth, towards the moon I get that Earth's mass is very large, so its acceleration is very tiny. But wouldn't the acceleration accumulate over a period of time and become noticeable? 4answers 847 views ### Gravitational effects of a single human body on the motion of planets (This is going to be a strange question.) How big a difference does the existence (or positioning) of a single human body make on the motion of planets in our solar system, millions of years in the ... 2answers 40 views ### Weighing machine, kg vs. N When I stand on a weighing machine and it shows me the number 75 , is it my mass in Kg or the Normal Force due to gravity in N 1answer 43 views ### Horizontal Free Fall Let's say you are launched out of a canon at a$0^\circ$degree angle 5 feet off of the ground. Normally, from my basic understanding of free falling, you have to be move unimpeded with no force ... 2answers 83 views ### Feynman's proof for Newton's shell theorem [closed] I have two questions concerning this proof: Firstly, what is the difference between the increments ds and dx? Are they not just the same thickness of the strip? Secondly, why can the integral ... 3answers 10k views ### How does the Earth's center produce heat? In my understanding, the center of the Earth is hot because of the weight of the its own matter being crushed in on itself because of gravity. We can use water to collect this heat from the Earth and ... 2answers 125 views ### Trajectory of a satellite whose velocity is less than circular orbital velocity? [closed] If the velocity of the satellite orbiting around a planet is reduced somehow...then what would it's trajectory looks like spiral(1) or elliptical(2) Or Does it depends on the velocity it has(less ... 1answer 77 views ### Why should Vector Components of a Weight be Perpendicular to each other? So this question came to my head this morning. When analyzing such a problem, its easier to break the W component into 2 seperate components, here I've marked the components in Red & Pink arrows. ... 1answer 40 views ### Newton's Laws of Motion - Two spheres in a cup [closed] This is the question I got really confused over: I tried drawing the free body diagram of the sphere on the left. Now if we let the angle between the vertical plane and$N_1$be$\theta$, this ... 0answers 46 views ### Does Earth's apparent gravity actually increase when I go to, say, the bottom of the Marianas Trench - or into a deep mine shaft? [duplicate] In a simple model, Earth's apparent gravity peaks at the surface. It falls off as$1/r^2$as we travel upwards, and it falls linearly as we approach the center of the Earth where it is zero. However,... 2answers 53 views ### Gravity “sorting” and French Press coffee I have read about the Earth's sorting of different-sized grains of sand and such. Larger particles are supposed to fall through water faster. I've seen it demonstrated before and have full faith. But ... 1answer 56 views ### Definition of “tidal forces” May anyone give me definition of tidal forces? Topic is related to force between two celestial bodies which are tidally locked. I have never heard for such force. Here is quotation which is intriguing ... 1answer 57 views ### Help with Gravity Assist [closed] In our scenario, a spaceship of mass 70,000 kg and velocity$v_o$is planning on slingshotting around Earth and we're supposed to find what the exit velocity will be. The Earth is the origin in our ... 6answers 8k views ### Why aren't satellites disintegrated even though they orbit earth within earth's Roche Limits? I was wondering about the Roche limit and its effects on satellites. Why aren't artificial satellites ripped apart by gravitational tidal forces of the earth? I think it's due to the satellites being ... 2answers 1k views ### What are the forces behind the orbit of the Earth around the Sun? Does the gravity of the sun alone affect the orbit of the earth around the sun? Look at the image below,(Image is not to scale), Is it that when earth is going from position 1 to position 2, it ... 1answer 45 views ### Contractions between big bang and gravitational law [duplicate] If big bang happened then the centre of the universe must be place of big bang. Let the mass of whole universe be$M$and mass of small planet or any Astro object be$m$. Then the Gravitational ... 1answer 44 views ### How to calculate the gravitational binding energy of a uniform cube of length$L$and mass$M\$?

The functional form is known already (as attached). But what is the solution for this integral?
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### Direction of gravitational field given equipotential lines

I've attached the question as an image below as it's a graphical question. It simply states: "The diagram shows equipotential lines near a group of asteroids. Which arrow shows the direction of the ...
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### Revolution of Earth around the Sun

We study the orbit of many planets around the sun modelling it as a uniform circular motion. Is this due to the fact that empirically we measured that the magnitude of the earth's velocity (for ...
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### Does gravity affect the time evolution of a QM wave function?

We know that the Schrödinger equation describes the time evolution of a wave function, but how does gravity affect that evolution? For example, does the wave spread slower in a strong gravitational ...
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### Correction to Newton's law of Gravity for dark energy

Is there any correction to Newtons law of Gravity that takes into account the expansion of the universe?
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### Given that the Moon affects tides and most of the human body is water, do tides affect people?

It is known that the Moon causes tides. Given that the human body is 60%-70% water, is there any research that shows that the tides affect humans in any tangible way? If this is not the appropriate ...
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### Why does the Earth follow an elliptical trajectory rather than a parabolic one?

I was taught that when the acceleration experienced by a body is constant, that body follows a parabolic curve. This seems logical because constant acceleration means velocity that is linear and ...
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### How to get the height of a constrained, infinite elastic surface?

Suppose I have an infinite elastic sheet, constrained by several poles of height 1. The height of the surface would be 1 at the coordinates of each of the poles, and converge to 0 as the distance from ...