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

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The force of gravitation [on hold]

Which is greater: attraction of the Earth to 5 kg of iron or attraction of 5 kg of iron to the Earth? give reasons. When an apple falls towards the Earth, the Earth moves up to meet the earth. Is ...
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47 views

Numerical problem related to Newton's Law of Gravitation [on hold]

Two iron spheres whose volumes are $38810 cm^3$ and $310464 cm^3$ respectively. If they are placed touching each other, calculate the force of gravitation between them. (Density of iron=$7860 kg/m^3$ ...
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1answer
319 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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2answers
216 views

Does rotation cause gravity? [on hold]

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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0answers
29 views

projectile motion under the influence of gravity [closed]

A projectile launched vertically from the surface of the Moon rises to an altitude of 330km What was the projectile's initial speed? vi= ______ m/s
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1answer
27 views

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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2answers
219 views

Confusion about gravity

I understand the “rubber sheet” model of Relativistic gravity is just an illustration, and beyond the initial issues of mixing three dimensional objects with a two dimensional representation of 3D ...
1
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1answer
41 views

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 ...
142
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9answers
36k 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 ...
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4answers
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 ...
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1answer
820 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 ...
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0answers
45 views

Gravity & centripetal force [closed]

Ok - My question rephrased, how are these three fundamental forces unified ? The Earth spins at a certain rate, it must follow that any object not attached must experience an out ward thrust. The ...
6
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4answers
26k 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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39 views

Dynamics of pairwise distances in the $n$-body problem

Consider the $n$-body problem where we are interested in describing the time evolution of $n$ masses interacting through a potential $U$. Let $D$ be the matrix containing all pairwise distances ...
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2answers
167 views

Expression for Atmospheric Pressure with Altitude, including Tidal Forces

Is this simple to obtain? I've tried to modify the constant-gravity model to use the $GM/r^2$ form instead, but my result was shown to be wrong with some testing. Constant Gravity Model You can ...
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0answers
20 views

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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0answers
31 views

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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0answers
18 views

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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1answer
19 views

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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5answers
177 views

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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3answers
34 views

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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2answers
217 views

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 ...
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2answers
753 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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1answer
133 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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1answer
23 views

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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1answer
35 views

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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3answers
40 views

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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4answers
62 views

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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2answers
456 views

Kepler's laws to determine radius of circular orbit

"In nonrelativistic limit of general relativity there is a correction to the Newtonian gravitational potential energy $−h/r^3$ with $h = αL^2/(mc)^2$, where $c$ is the speed of light, $α = GMm$ ...
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1answer
26 views

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. ...
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1answer
71 views

Can I re-wind gravity?

Suppose I perform an arbitrary simulation where I integrate the motions of a collection of particles which interact only gravitationally. Suppose I use a time reversible integrator (to be specific, ...
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0answers
15 views

Gravitational intensity in the real sense [duplicate]

Gravitational intensity inside a hollow sphere is zero. Then if we were able to insert a body of mass $m$ exactly at the centre does it experience gravitational force. Does it fall or float?
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1answer
35 views

Energy diagram of a planet with fixed mechanical energy

Consider the following energy diagram for the motion of a planet about a star. The centrifugal potential curve can be represented once I fixed the angular momentum $\vec{L}$ of the planet. To fix the ...
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0answers
59 views

Why is there no negative mass? [duplicate]

We know that the entire matter has a property called mass. Charge is also a property of matter. If negative charge can exist, why don't negative mass exist? Also, like charges repel each other. Then ...
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0answers
16 views

Why is graviton not found yet? [duplicate]

Why is graviton not found yet? Newton said gravity pulls us, Einstein said space is bent and it pushes us, hawking predicts the existence of graviton and 'hawking radiation'. How far are we from ...
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0answers
31 views

Celestial bodies trajectories relative to each other and with respect to the CM

In a two bodies $A$ and $B$ system, both under the action of an internal force of interaction $\vec{F}$, the motion of $A$ as seen from $B$, is equivalent to the motion of a single body of mass ...
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1answer
34 views

Infinite acceleration of bob in pendulum with no friction or air resistance

So i'm a bit confused about something. If we take a mathematical pendulum and we apply a force to it. We ignore all friction and air resistance and only consider gravity and the force applied to bob. ...
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1answer
42 views

Angular Acceleration of a Pendulum

I am trying to work out the mathematics behind the design of an old mechanical brake tester. The device sits in the passenger foot well of a vehicle and tests the brake efficiency. The device is ...
4
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2answers
160 views

Fired a bullet upwards, can it fall down and kill me?

I know that if something is thrown up with a velocity v, it comes down with the same velocity as long as its motion faces no resistance. So is it possible for me to fire a bullet and be killed if it ...
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5answers
21k views

Why doesn't mass of bob affect time period?

The gravitation formula says $$F = \frac{G m_1 m_2}{r^2} \, ,$$ so if the mass of a bob increases then the torque on it should also increase because the force increased. So, it should go faster and ...
2
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2answers
565 views

Tangential and radial acceleration in projectile motion

I'm currently learing kinematics, specifically projectile motion and as an example in my textbook is a bullet fired at some angle. I understand the derivation of formulas to describe that motion and ...
8
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3answers
2k views

Does the mass of a star change as it collapses into a black hole?

I know (I think!) that when a really big star collapses on itself it creates a black hole. My question: When a star collapses, is the mass equal to the mass of the star when it's not a black hole? Or ...
6
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5answers
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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 ...
3
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2answers
195 views

Climbing Stairs and Calories Burnt

I climb stairs to work (20 floors) every day . The least amount of work my body is doing by gaining potential energy (P.E) = mgh where m is mass , g is acc. due to gravity and h is height . Assuming ...
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1answer
27 views

How does the total change in energy being negative indicate the direction of the Force?

To be more precise consider the following situation: Suppose a satellite is orbiting at a distance of $r_1$ from the centre of the earth. After some time, rockets are fired such that the new distance ...
5
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6answers
122 views

Why do constants have dimensions?

I am just a beginner in dimensional analysis, and I see that $G$, the universal gravitational constant, is independent of everything. Speed, for example, depends on distance and time, but $G$ does not ...
5
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2answers
808 views

$1/r^2$ gravitational force of triangles in 2D

Suppose I have two triangles relatively close together (so they probably shouldn't really be treated as point masses). I want to calculate the gravitational force (and potentially torque?) generated ...
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4answers
66 views

Question related to accleration due to gravity [closed]

What effect will be seen on the value of accleration due to gravity if radius of the earth is decreased keeping the mass constant?
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1answer
31 views

Orbiting in space (free fall) and centripetal force?

So basically astronauts are weightless b/c they are free falling. But to get to that state they need to be moving real fast. So why doesn't that speed along with the centripetal force affect them? I ...