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

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Inertia and Rocket Propulsion

We were taught in school that the law of inertia indicates that an object tend to stay the way it is, so if you throw something in space it will tend to go on forever and ever. The reason an object ...
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2answers
359 views

Do heavier objects fall faster? [duplicate]

This question has been asked multiple times here and all over the internet yet I can't find a conclusive answer: Some claim that heavier objects do fall faster: Don't heavier objects actually fall ...
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3answers
689 views

Archimedes' principle for two liquid layers

Problem: I have a cylindrical vessel of height $H$ and radius $R$. There are two liquid layers in the vessel. The first has density $D_1$ and height $h_1$, the second has density $D_2$ and height ...
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1answer
647 views

Newton's second law, gravity and buoyancy [closed]

A body of mass $m$ and volume $V$ is immersed into the sea. The body moves under the action of two forces: gravity and buoyancy (Archimedes). Gravity force has a magnitude $mg$, where $g$ is a ...
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2answers
314 views

Does earths gravitational force vary depending on where you are on the planet?

Does the gravitational force acting on a person ever change just by their position on the planet. For instance, at greater altitudes or closer to the equator.
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1answer
527 views

Will a free-falling rod (without drag) rotate?

When we consider a bicycle is turning on a flat plane, we know that there is friction, which provide centripetal force on the bicycle. And we know that the bicycle is no longer perpendicular to the ...
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2answers
780 views

Why do orbital speeds decrease further away from the focus?

Why do orbital speeds decrease further away from the focus? A simple question, but I want to make sure I am understanding this correctly: Is it ONLY a function of the gravity well? As in, the ...
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1answer
568 views

Why do you experience low-gravity outside the Earth (but near it), and experience more gravity on it?

Spacecraft, satellites, etc. They also experience zero gravity, weightlessness, or "micro gravity" when outside Earth, about 20-300+ miles beyond the escape velocity zone("atmosphere"). However, you ...
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3answers
653 views

How does artificial gravity reduction (weightlessness) work on Earth?

Some of us have been to those amusement park/carnival/theme park rides where you enter some capsule/machine, and you will float, etc. There is also some other thing where you go inside a big room ...
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2answers
117 views

Origin of cusps in simulated dark matter halos

I keep reading that cusps are one of the most "robust" predictions of N-body simulations of dark matter halos. But papers I've found on the topic make it sound like these simulations are complicated ...
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1answer
2k views

Proving Kepler's 1st Law without differential equations

Is there a way to show that motion of Earth around the Sun is elliptical (Kepler's 1st law) from Newton's laws without resorting to the use of differential equations of motion?
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2answers
591 views

Why is there no permittivity-type constant for gravitation?

When I look at electric or magnetic fields, each of them has a constant that defines how a field affects or is affected by a medium. For example, electric fields in vacuum have a permittivity constant ...
2
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1answer
451 views

How do we know the Earth orbits around the Sun and not the other way around? [duplicate]

I know that describing the trajectory of all planets in the solar system around the Earth is much more complicated than if we take the Sun as the reference point. But besides this, what is the ...
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1answer
291 views

Value of of gravity 9.8m/sec^2 and centrifugal force [closed]

I had a doubt regarding centrifugal force on earth is not accounted in any equations as object falling towards earth.eg f=ma.i read questions asked by few about the same and got to a conclusion that ...
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2answers
246 views

Under what conditions, will a projectile motion follow a half circle?

What came to my mind is to throw an object far from the earth with a particular speed equal to $$V_{sat}=\sqrt{\frac{G\times M_{central}}{R}}$$like satellites. However, it would follow a full circle.
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0answers
85 views

Planatary motion of newtonian force [closed]

According to the Newtons gravity we can write, $$\vec F = \frac{\hat r_{12} G m_1 m_2 }{r_{12}^2}$$ and we are well known that this law satisfies the planetary motions. What changes will we see if we ...
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1answer
77 views

Evaluating $v$ for orbiting a golfball [closed]

The curvature of Mars is such that its surface drops a vertical distance of 2.0 meters for every 3600 meters tangent to the surface. In addition, the gravitational acceleration near its surface ...
38
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2answers
1k views

Can we infer the existence of periodic solutions to the three-body problem from numerical evidence?

I recently found out about the discovery of 13 beautiful periodic solutions to the three-body problem, described in the paper Three Classes of Newtonian Three-Body Planar Periodic Orbits. Milovan ...
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1answer
210 views

Determine if an object is in orbit

I am planning on doing a space simulation program with full physics and as part of a hack to avoid too many issues with number precision I was going to switch orbiting objects to a calculated orbit ...
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1answer
10k views

String tension in vertical circular motion

Suppose that I have a point mass attached to a massless string and I am rotating it vertically. That means The mass is in uniform circular motion and the path of its motion is vertical circle. How ...
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2answers
1k views

Explain what happens to object in lift [closed]

In the following image,three cases have been mentioned. $N$ is the normal force acting on the object inside the lift and $mg$ is the force of attraction due to gravity. In case 1, $N = mg$. In case ...
5
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4answers
2k views

Gravity - What happens when two objects of unequal masses fall freely towards the ground? (Revisited)

The common perception regarding what happens when two objects of equal sizes but unequal mass are allowed to fall freely towards the ground is that - both the objects make contact with the ground at ...
2
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0answers
56 views

Where are the L3, L4, and L5 points of a hyperbolic orbit?

Do the L3, L4, L5 points exist in hyperbolic orbits? If yes, then where do they lie?
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1answer
476 views

Details of the new solutions to the three-body problem [closed]

This question is part of this week's Journal Club session. These systems look ridiculously fun to construct. Could someone explain the particulars? What are the various types of solutions, and ...
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1answer
181 views

How does physicists calculate the gravitational self collapsing force of a star?

The nuclear fusion taking place inside the stars opposes its gravitational self collapsing force. But, how does physicists calculate it? I just know the classical gravitational theory and not a bit of ...
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1answer
127 views

Is the trajectory of the Moon around the Earth stable? [duplicate]

I understand how mathematically is possible to have one object with elliptical or circular orbit around another object in space. so can I think of it as a limit cycle? If yes, then is it stable or ...
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3answers
753 views

Why does a bicycle come to rest after travelling a distance?

According to Newton's law of motion, an object that is in motion will not change its velocity unless an external force acts upon it. In the case of a bicycle, if it is in motion with a certain ...
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1answer
154 views

Does Archimedes law depend of lack of matter?

I would like to know if Archimedes law take in equation the lack of matter. Fluid density at 1. An object with density of 0 (or near 0) is put in liquid, it's fixed. The external sphere where liquid ...
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1answer
41 views

induction for massive objects

We know that when two charged bodies are kept near one another, they attract the charges and induce some charge near the surface. This happens even when only lne body is charged as the charges are ...
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1answer
977 views

What is the precise definition of Gravitational Sphere of Influence (SOI)?

I am trying to understand the gravitational sphere of influence (SOI), but all I get by searching is the formula that you can find on Wikipedia, that is $$ r_{SOI} = a \left( \frac{m}{M} ...
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3answers
159 views

Why heavier bodies produce greater gravitational pull than the lighter bodies?

The basic question "Why planets revolve around the Sun?", is explained by taking into account the heaviness of Sun. The lighter bodies are considered to move around heavier bodies,as like lighter ...
5
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0answers
132 views

Victorian cosmology after the second law of thermodynamics but before relativity?

In the 19th century, most astronomers adopted an island universe model, in which our galaxy was the only object in an infinite space. They didn't know that the "spiral nebulae" were other galaxies. ...
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3answers
2k views

If there is no gravity, does that mean there's no mass as well?

I have demonstrated that weight only is measured based on the gravitational pull of where you live. For example, the gravity on the surface of Mars is three times smaller than the gravity on the ...
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1answer
153 views

Is this object turn alone with torque inside disk of water?

This is not the original question, I changed for explain details. But now it's not possible to delete the question and now the reply is not in relation with question. I post a new question, and try to ...
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4answers
367 views

Why is there no gravity in the center of a celestial body, yet there is gravity on the surface? [duplicate]

I've heard few explanations, but none in good detail that make it clear to those with less mathematical knowledge on the equations of complex physics. I would like to think that since you are on the ...
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3answers
1k views

Why gravity decreases as we go under ground? [duplicate]

We all know that gravity decreases as we go upward, we also know that gravity decreases as we go inside the earth? I don't know why gravity decreases as we go downward or inside the Earth? Please ...
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0answers
45 views

The magnitude of spacecraft anomalous velocities?

That Voyager and several other spacecraft have had anomalous changes in speed is known. According to the news reports, the differences are unsettling. But just how large are these anomalies really? ...
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1answer
176 views

Variational principles: Meniscus

In determining the shape of a meniscus, we have to minimize the energy per unit length along the direction perpendicular to the cross-section of the meniscus: $$\frac{E}{L}=\int^L_0 dx [\gamma ...
2
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3answers
413 views

How accurate is Newtonian Gravity?

I know that really fast moving things need Relativity rather than Newtonian physics. I also know the quirk of the Mercury´s orbit. But just how much more accurate is General Relativity than Newton´s ...
3
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1answer
151 views

Is it possible to levitate an object with piezoelectricity?

The delay for transmit pressure depend of speed of sound in the material. A lot of piezo slip-stick actuator can generate an asymetric wave. Like the differential pressure is not the same the force to ...
2
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3answers
343 views

Can I make a rod in the vertical plane move with its one end on the ground in a slanting position?

Consider a rod kept vertically on the ground. I keeps the rod in a slanting position making some angle with the horizontal. Can I now move this rod along the horizontal plane by applying a force at ...
2
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2answers
455 views

Signs in proof of gravitation potential energy (GPE)

Proof of gravitational potential energy. Work done by gravity in bringing mass from infinity to a distance of $r$ between masses. When we use the integration formula and arrive at the answer we ...
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1answer
412 views

In a moving bus will the ball fall behind me when tossed?

Using Newton's law I have to find whether in a moving bus will the ball fall behind me when tossed in air or will come to me only or will fall in front of me. In fact there are two cases; 1- Bus ...
4
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8answers
666 views

Why in Newton's law of gravity, we do $M_1 \times M_2$ and not $M_1 + M_2$?

In Newton's law of gravity $$F=\frac{G M_1 \cdot M_2}{r^2}$$ we do the product $M_1 \times M_2$ and not the sum $M_1 + M_2$. Why's that so?
3
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1answer
328 views

Why closed bottle change its weight when I put effervescence tablet?

I use several shape, several type of material (glass, metal, plastic), I use two different balances with 0.01g of accuracy. I put oil on gasket, and put upside down (like that I can see if water ...
0
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1answer
252 views

Ball on a slope [closed]

I have a lab report, but I can not write it in a correct way. The lab experiment was about a ball rolling on a slope, I have a height of the slope, the distance, and the time in which the ball spent ...
2
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2answers
323 views

Mathematical model for this graph of a simplified binary star system?

Unnecessary background for question: I had a school assignment asking us to relate a quadratic equation to a real life example relating to our future dream career, making sure to express the accuracy ...
2
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4answers
2k views

Gravitational Potential Energy (GPE) to Kinetic Energy (KE) transfer in Satellite Orbits

I am stumped by a mundane A Level Physics question (teacher of physics here obviously a bit short of practice!). My colleagues and I are stumped and were wondering if any one could help us. It ...
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2answers
115 views

How Galaxy is formed?

Given the distance among stars (the most massive objective in the space) is so huge, the difference of order of magnitude is about 7. And also, since gravity is such a weak force, how is it likely for ...
2
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1answer
292 views

Gravitational binding energy and integrated potential energy not the same?

Before looking up the formula for the gravitational binding energy of a uniform sphere, I simply figured that the general formula for binding energy of an arbitrarily-shaped mass distribution would be ...