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

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Athletics on the moon [on hold]

The moon is a lot smaller than the earth ($\frac{1}{81}$ of the mass and $\frac{3}{11}$ of the diameter). a)How high would a professional vaulter jump on the moon? Assume that he would jump ...
-3
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0answers
28 views

How to calculate the gravitational force from Earth to Moon? [on hold]

I know the $G$ constant and the distance. Also I tried with Mass of Earth.
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5answers
264 views

Resolving General relativity and Newtonian mechanics to a computer [on hold]

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
63 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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2answers
62 views

Why does Earth accelerate every object toward itself with acceleration of $9.8\, m/s^2$ [on hold]

Why Earth accelerates objects due to gravity with $9.8\,\mathrm{m/s}^2$. How to demonstrate that?
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1answer
53 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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0answers
26 views

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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2answers
1k views

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 ...
-2
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0answers
20 views

3 point masses;circumference [duplicate]

3 gravitating mass points of mass m are on the circumference of a circle with the same distance r to each other. At $t=t_0$ one lets go of the mass points and each of them moves within the ...
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1answer
18 views

How does newtons third law help explain interaction between charged objects? [closed]

I was reading an article and this came up if someone can please explain.
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52 views

Gravitating masses on a circumference [closed]

3 gravitating mass points of mass m are on the circumference of a circle with the same distance r to each other. At $t=t_0$ one lets go of the mass points and each of them moves within the ...
0
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0answers
10 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
26 views

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
40 views

What is the acceleration of a charged particle in uniform electric field [closed]

I would guess its $kC/r^2$, just like the in the context of gravitation, as one arrives at the acceleration due to gravity $g = GM/r^2$; but I am not sure.
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1answer
62 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? ...
0
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1answer
54 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 ...
0
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1answer
51 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 $R$ ...
2
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0answers
89 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 ...
2
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1answer
38 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 ...
2
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3answers
136 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?
0
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1answer
44 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
votes
2answers
207 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 ...
2
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0answers
23 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
66 views

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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4answers
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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 ...
0
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3answers
111 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
42 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 ...
13
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5answers
2k views

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
201 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 ...
2
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1answer
44 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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0answers
44 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
41 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?
1
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1answer
70 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
32 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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0answers
38 views

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
83 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
52 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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2answers
61 views

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
80 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
35 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 ...
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2answers
34 views

will the acceleration of a freely falling body having rotional motion be differet from g?

A disk is falling freely vertically rotating on its on axis while doing so. Will the acceleration of the body be different from 'g'?
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0answers
23 views

References on the 3 body problem

Does anyone know good references for the general 3 body problem? I'm looking for both analytical and numerical approaches.
0
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1answer
49 views

Why Earth is not a cuboid? [duplicate]

There must be some scientific reasons for why earth is a spheroid but what are they? If Earth would be a cuboid, Would it matter?
1
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2answers
133 views

If Earth and Jupiter are orbiting around Sun in same orbit, will they have same time period?

Let us suppose that Earth and Jupiter are orbiting around the Sun in same orbit, If we talk about at any particular point. (Which is not possible but for the sake of question) I was wondering that ...
26
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5answers
5k views

Is there any disadvantage to sending rockets straight up?

When we send satellite into space using a rocket, logically we consider the shortest path which is a straight line perpendicular to Earth's surface. My question is do rocket takes the shortest path to ...
1
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3answers
69 views

Negative density solutions of the Poisson's Equation for polytropic gas (aka Lane-Emden Equation)

Question: What does it mean by when we obtain negative density for specific region in space as a solution of Poisson's equations? I will explain the situation as detailed as possible, so that anyone ...
0
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2answers
62 views

Free-Falling Object

How does the presence of air affect the rate at which a body falls? What is the rule for falling objects, when there is little or no air resistance?
14
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6answers
2k views

Can you ever exert more downwards force than your weight?

So, because I'm a hardcore person, I risked all this afternoon by going out in the wind, the rain and the cold to construct a willow den. Yes, it seems a menial task, but it was actually quite ...
0
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3answers
78 views

On a scale, why does the heavier object go down?

When you balance a pencil on your finger, I have always wondered, "Why does the heavier part go down, and the lighter, up?"
0
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1answer
40 views

Does mass distribution/center of mass affect free fall?

An everyday is example would be cars. If you were to drop a car, not taking air resistance into account, would a front-heavy car tumble forward as it fell? And a car with a perfect 50/50 front/rear ...