# Tagged Questions

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

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### Orbital parameters of more than two bodies

I am not even entirely sure that the question makes sense except in certain simple cases, but let me explain what I am trying to do, but with the question first. The question is essentially: Given n ...
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### Gravity Sun Earth Moon [duplicate]

The gravitational pull the Sun has on the Moon is roughly two times greater than the pull the Earth has on the Moon. If this is the case, why does the Sun's gravity not pull the Moon away from the ...
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### Centre of gravity of system [closed]

We have a uniform rectangular tray of dimensions 40x60, with weight 3. We place the coordinate axes in such a way that the bottom-left corner of tray is at the origin and the tray sides are parallel ...
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### falling in a gravitional field [duplicate]

It is often stated that masses fall at the same rate towards the Earth at the same rate (barring things like friction), and this seems to be quoted as the Equivalence Principle. Is this statement ...
11k views

### Orbital speed for a circular orbit?

I wanted to look up the formula for orbital speed for a circular orbit on Wikipedia, and I found 2 formulas: All bounded orbits where the gravity of a central body dominates are elliptical in ...
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### Velocity Related To Gravitation [closed]

Which Equation is correct $v^2=\large{\frac{2GM}r}$ OR $v^2=\large{\frac{GM}r}$? I am getting confused here.
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### Why did Trebuchet have so long throwing arms?

Have a look at such an historical Trebuchet: As you can see, the throwing arm (left) is much longer than the weight arm (right). Law of conservation of energy says, potential energy from the ...
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### Why the pressure in liquids only depends on the height?

look at this picture : and also look at this one: imagine that the surface area of both is the same and both of them are full of water. My question is that why they both are pressing the beneath ...
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### Gravitational acceleration of asteroids [closed]

If an asteroid is moving through space at a speed that exceeds escape velocity of the earth and that asteroid is on a collision course with the earth will the asteroid Accelerate as it falls into the ...
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### About the use of Newtonian Relations for the movement of stars in the Galaxy [duplicate]

From a General Relativity point of view Gravity is given as the result of spacetime curvature interacting with energy-mass density. To get to the Newtonian limit one needs to take a) Non-...
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### Does Earth's Rotation Affect Its Shape?

The question I am working on is, "Consider the following. (a) Find the angular speed of Earth's rotation about its axis. rad/s (b) How does this rotation affect the shape of Earth?" I am ...
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### How is the centrifugal force responsible for Earth's oblateness? [duplicate]

I'm having serious problems understanding the centrifugal force caused by Earth's rotation. How does it affect the Earth's shape? Should I draw the gravitational acceleration (the one in Newton's ...
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### Why it's more difficult to walk in an inclined plane than in a causal road [closed]

my question is about something very casual , but when i tried to solve that , it was not easy at all . My question is : "Why when we walk in an inclined plane we get tired more than when we walk in ...
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### Need motion equations for falling ball for simulating [closed]

I am currently M.S student in artificial intelligence(A.I) and working on my thesis on reinforcement learning, which robot should learn by itself how to control a quadcopter. Long story short, I have ...
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### Finding an object's final velocity with distance dependant force [duplicate]

I am (just for fun) trying to calculate the velocity with which the moon would impact the earth if it stopped orbiting and simply headed towards earth. I know the force is $\frac{G m_1 m_2}{r^2}$. ...
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### Why doesn't orbital body keep going faster and faster? [duplicate]

If we consider the change in velocity during an infinitesimal interval of an orbit: where body B is orbiting body A, we can see that the magnitude of the resultant vector (the green arrow) is ...
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### Will centre of gravity coincide with centre of mass if density of object is non uniform?

I read that for bodies of very large dimensions, but having non-uniform density, the centre of gravity does not coincide with centre of mass. I can understand that with large dimensions the strength ...
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### Why Sun is not able to attract mercury closer?

As sun have a huge amount of attraction pull force , why its not able to pull tiny mercury? Is the whole solar system works in a push and pull network? Why bigger planets like earth, Saturn and ...
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### Why doesn't an orbiting body keep accelerating?

As a physics newbie I'm trying to get a grip on basic orbital mechanics. I think I'm beginning to get grasp on how bodies interact with each other. When a body approaches another body it accelerates ...
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### Why is the gravitational constant so difficult to measure?

The gravitational constant seems to be very low precision. For example, in the Wikipedia article recent measurements are given as having the significands of 6.67 and 6.69, a difference of 2 parts in ...
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### What factors will make Earth re-rotate again if it stopped? [closed]

"What will happen if Earth stopped rotating?" have been answered multiple times with a lot of informative and interesting answers. Continuing this hypothetical question, I have another one in mind. ...
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### Sun's tidal force on Earth

My question is regarding effect of Sun's gravity on earth. I want to know that if Sun's gravity can change Earth's landscape in long duration (i.e. billion of years) or not? Means if earth is dead ...
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### How does Modified Newtonian Dynamics (MOND) violate Newton's laws?

I have read some articles on MOND which indicate that a modification of gravity violate Newton's third law, but I don't know how exactly that works. I do know that if Newtonian acceleration is smaller ...
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### What is exact difference between gravitational force and magnetic force? [closed]

I've read that gravitational force is due to mass only and magnetic field is due to moving charged particles. But my question is: what are other difference between them? Can we set up a small ...
7k views

### If we threw a baseball from the ISS, could we deorbit the ball?

Clearly this is a hypothetical question. Say we bring a star baseball player into NASA, prep them appropriately for a mission in space, and fly them up to the International Space Station. They go on ...
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### Calculate the speed of Halley's comet at his perihelion [closed]

Knowing that Halley's comet orbita the sun every 75,3 years, that the semi-major axes is 17.83 AU, the semi-major axes is 4.53 AU and at his perihelion he is 0.586 AU away from the sun. With these ...
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### Why can't one see tidal effects in a glass of water?

Why can't one see the tidal effect in a glass of water like in an ocean?
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### How would I find the velocity of an object after it doesn't fully enter the gravitational pull of a planet and is kind sling shot out of its gravity?

Obviously that question doesn't have a lot of jargon having to do with math and physics. I am not a physicist, I'm not a mathematician, I'm trying to make a game and simulate some physics found in ...
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### Does the human body have a measurable gravitational field?

I am researching communication other than speech or vision. The human body emits radiation in the form of heat; As the body has mass, will it have a gravitational field?
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### Does rotation cause gravity? [closed]

I want to ask that what causes gravity. My opinion is that it is the rotation that causes gravity, when we see a whirlpool in water it takes anything that comes near to it in to the center of it. I ...
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### Moment of inertia and gravity

Would the objects have moment of Inertia if there was no gravity? Because imagine a bar, if I put my hand at the center of the bar and rotate it, it would be easier than rotate the bar picking one ...
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### Free fall in non-uniform field

Imagine I'm a space-diver, with mass $m_1$, 500 miles above the Earth's surface at $x_i$. I want to calculate my position, velocity, and acceleration as a function of time, accounting for the Earth's ...
37k views

### Don't heavier objects actually fall faster because they exert their own gravity?

The common understanding is that, setting air resistance aside, all objects dropped to Earth fall at the same rate. This is often demonstrated through the thought experiment of cutting a large object ...
2k views

### How much does the Earth's rotation affect a golf ball?

When launching rockets into space, they start straight but begin to lean, I assume due to the Earth's rotation. For something on a much smaller scale, such as a golf tee, is there a measurable ...
843 views

### Defy gravity torques with gyroscopes?

Context On the following drawing, a platform is hung from the ceiling not exactly from its centre of gravity. Because of this it can't sustain an arbitrary orientation for long; I want to increase ...
31k views

### Why is Earth's gravity stronger at the poles?

Many sources state that the Earth's gravity is stronger at the poles than the equator for two reasons: The centrifugal "force" cancels out the gravity minimally, more so at the equator than at the ...
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### Do all objects free fall at the same rate regardless of their mass? [duplicate]

Is it true that all object will fall at the same speed in vacuum irrespective of their mass because the acceleration due to gravity of Earth is 9.8 m/s2. Then what happens to the gravitational force ...
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### If gravity on a non-rotating body suddenly stopped, would an object on the surface fly away? [closed]

This is a very trivial question, and I tried to word the title as concisely as possible, but I can't seem to figure it out. This is not referring to any hypothetical discussions regarding Earth. ...
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### Do greater mass objects attract objects quicker, than lessor mass objects? [duplicate]

If I jumped up and down on the moon it would take longer than if I jumped up and down on earth... the only changing variable being mass - the difference in mass between the earth and moon. wouldn't ...
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### Will the distance still be measured from the centre? ( During gravity measurements)

I have read that to find the gravitational force between two objects, we need to have the distance between their centres. Now if i have an object whose centre is not on it’s body ( as in a ring ), ...
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### Why do heavier objects fall faster on hills but not in straight drops?

All other things being equal, if a heavier object will roll at a higher speed down hill than a lighter one, because it's heavier with more mass, then how is it that dropped objects fall at the same ...
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### Relationship Gravitational Potential and the Tangential Velocity of a Satellite

So gravitational potential is given by $V(r)={\frac{GM}{r}}$ and the tangential velocity of a satellite is the square root of $V$, i.e. $\sqrt V$. So how do these two relate, if at all?
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### Bending of light - photon's inertia instead of mass

Using classical mechanics, the formula for gravitational attraction is $$F = G\frac{m_1m_2}{r^2}.$$ This formula does not work for photons, and we need to use Einstein's theory of gravity to ...
834 views

### What is the terminal velocity of a sheep?

Inspired by this question on Gaming.SE Using actual in-real-life physics, what would the terminal velocity of a sheep actually be? I would assume it would be around 50m/s, but I might be wrong. ...
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### Finding mass with an estimated gravitational force

As asteroids orbit the sun, they experience gravitational force exerted on them by the sun, and they in turn exert a very minute force back on the sun. Because of their small size, asteroids don't tug ...
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### Vector interpretation of Kepler's 2nd law ( r X a = 0 )

I just read the vector interpretation of Kepler's second law and the conclusion put me in a confusion. The interpretation concludes by demonstrating that r X a = 0, where boldfaced r and a are ...
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### How to calculate projectile path having starting and end point?

I want to show a projectile path between two points (x1,y1) (x2,y2 ) on graph. Here I know two points, start point and end point. I tried solving by taking launch angle as 45 degree, it doesn't seem ...
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### Why are objects (such as planets) in motion and not static? [duplicate]

I am just curious, why are all the planets, rocks etc in motion? Would they fall into objects with larger gravity if they were not in motion? What is stopping the earth from falling into the sun or ...
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### What is the gravitational field lines pattern of a sphere of mass $m_1$ in an open ended box of mass $m_2$?

This Quetsion is inspired by this Fig of a positively charged metal sphere in an earthed metal box:
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### Is there any experimental evidence to distinguish the total gravitational force exerted by the two proton and a helium nucleus?

I know that the sum of the mass of the two proton is greater than the mass of a helium nucleus (two proton). As the mass different is transformed into energy by the Einstein mass energy-equivalence. ...