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

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How much wind power is needed to lift someone up? [duplicate]

I'm talking about fan wind power. A range would be sensible from about 8yrs-50yrs as not all human beings are the same weight with the added weight of a 5kg engine and average skateboard.
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3answers
352 views

Power to suspend a mass in air

How much power is needed to suspend a mass in the air? The four parts below deal with the same problem. I post them all here, should there be some subtle things I didn't see. The textbook problem A ...
3
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0answers
56 views

Can one verify the Earth tide in his yard?

The ocean tide you can see on the coast. But the Earth tide beneath our feet is hardly perceivable. Is there any way to verify it in one's yard?
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1answer
308 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 ...
4
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3answers
207 views

What is an intuitive explanation using forces for the equatorial bulge?

The earth is not a sphere, because it bulges at the equator. I tried fiddling with centripetal force equations and gravity, but I couldn't derive why this bulge occurs. Is there (a) a ...
5
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5answers
4k views

Can a balloon float into space? (+orbital velocity)

After watching the recent "space jump" a question arose. Why can a balloon not float into space? Can one be made/designed to do this? Next, everything in orbit is falling back to earth. It only ...
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3answers
108 views

Is it possible for man to break Earth into 2 parts? [closed]

Many countries have extreme devastating nuclear weapons. Also they have weapons in very large numbers. I want to ask that Is it possible for man to break earth into 2 parts with the help ...
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1answer
39 views

Differential form of the law of gravitation potential

I have problem understanding transaction (operations and methods applied) for one equation to other equation. It is about gravitational potential. $${\vec F_{grav}=\frac{GMm_{obj}\vec R}{R^3}}$$ If we ...
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1answer
93 views

Calculate orbital changes after acceleration

With the vis-viva equation I can calculate the orbital speed at any position on the ellipse. I want to calculate the opposite way. Assume a satellite with an apogee of 600km and a perigee of 400km is ...
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2answers
117 views

Finding sphere of influence in multibody system

I would like to draw a boundary illustrating the sphere of influence of each body in a 3 body system. What is the best way to find such a boundary? My understanding is at the edge an SoI is the ...
1
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1answer
27 views

How may one calculate the escape velocity of a binary system at a given radius from the COM?

Apologies if this is a bit general, even some pointers in the right direction would be great (reading material etc.) Given an object of mass $m_3$ travelling outward at speed $v$ from the centre of ...
2
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1answer
101 views

Does the Earth gets closer to the Sun?

We know that the sun loses an amount of it's mass equivalent to the amount of energy it produces, according to the $E=mc^2$ equation. so the sun is losing mass every second. Does this affect the ...
0
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0answers
43 views

Gravity between Moon and Earth [duplicate]

It's known that the greater the mass the stronger its gravitational force. Hence, Sun's gravity is definitely stronger than Earth's. So the question arises that why does the Moon orbit around the ...
0
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5answers
113 views

How is energy conserved in this scenario?

There are two objects A and B of equal mass (m). They are laying in close proximity to each other. Object A is then moved further from object B, to a distance r. Since there is gravity between these ...
3
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3answers
271 views

Deceleration rate of objects of different mass but the same otherwise

Using a tennis ball as an example object, if one ball weighs 1 ounce and the other is 2 ounces, and both are struck at 100 mph on the same trajectory, would there be any difference in the deceleration ...
0
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1answer
53 views

Circular orbits in general relativity(GR)

Reading about Schwarzschild geodesics, I found that circular orbits are possible when the effective force $$ F=-\frac{dV}{dr}=-\frac{\mu{c^{2}}}{2r^{4}}\left(r_{s}r^{2}-2a^{2}r+3r_{s}a^{2}\right)=0 ...
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7answers
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Gravity on the International Space Station

We created a table in my physics class which contained the strength of gravity on different planet and objects in space. At altitude 0(earth), the gravitational strength is 100%. On the moon at ...
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4answers
7k views

Why doesn't mass of bob affect time period?

Please correct me if I'm going wrong - By the gravitation formula: $F = \frac{G m_1 m_2}{r^2} $, So if the mass of a bob is greater then the torque on it should increase because the Force increased ...
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2answers
100 views

Is there a mathematical proof show that :$F=G\frac{m_1m_2}{r²}$? [duplicate]

Is there a mathematical proof about The general law of attraction between two point masses $m_1$ and $m_2$ which represented as: $$F=G\frac{m_1m_2}{r²} ,$$where $r$ is the distance between the ...
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2answers
175 views

Why $1/r^2$ and not another power of $r$ in Newton's law of gravitation?

My book introduces the force of gravitation as a non-contact force between two bodies of mass $M_1$ and $M_2$ separated by a distance $r$ . Then it says it is directly proportional to the product of ...
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1answer
244 views

What is the simplest way to perform a Cavendish experiment?

The Cavendish experiment is cool, but seems complicated to experimentally perform. What is a simple way to recreate the experiment?
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0answers
45 views

Vehicle Driving off Cliff (Thelma and Louise movie)

What is the slowest speed at which a vehicle driven off a cliff can clear the cliff without catching its underside between the wheels? In the usual frictionless vacuum, this would appear to depend on ...
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2answers
748 views

How does gravity work?

The math, I read, is $$F = G\frac{m_{1}m_{2}}{r^{2}}.$$ What I'm unclear about is how does it work in practice. Say there are two identical pebbles massing 1 kilogram each outside Sol's gravity ...
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1answer
42 views

How close to the surface of the Sun would one have to be to determine an 'upright' position relative to it's surface?

As we stand upon the surface of the earth we're able to establish a relative 'up' and 'down' direction due to gravitational forces. As we leave the confines of the earths gravitational attraction ...
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2answers
61 views

Deriving the velocity for circular orbital motion

I'm trying to derive the (circular) orbital velocity for a given height from the center of mass of a body, like Earth. First I used the equation of the circle $x^2 + y^2 = r^2$ to get $y = \pm ...
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1answer
26 views

Weight vector dependence

Does the weight of a person depend on the number of people or other bodies in say a room? If so,why? Was thinking about it earlier and want to find out from others.
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2answers
346 views

Do the planets really orbit the Sun?

This is a duplicate of this question on Space Exploration.SE. So why would I ask it again here? Read below. The question reads We often say that the planets orbit the Sun, which is usually a ...
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2answers
43 views

Gauss law for gravitational field

Gauss's law is fundamental law of electrostatics. But Can we apply Gauss's law for Gravitational field also?
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3answers
79 views

Gravitational acceleration

'What is difference between free fall acceleration g and gravitational acceleration a?***a is with subscript g.In my textbook it is written that "free fall acceleration = gravitational acceleration - ...
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2answers
62 views

Physical Meaning of Cone used in Conic Section for Orbital Mechanics

Does the polar angle (complement of $\theta$ below) of a cone which intersects a plane to yield a conic section have a physical meaning in orbital mechanics? Note that the angle of incident ...
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1answer
34 views

Motion of a ball in a tunnel along Earth's diameter [duplicate]

Suppose, a tunnel is made along the diameter of Earth and we drop a ball inside it. How will the ball behave? Please help me in the stand.
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2answers
540 views

How did Newton discover the universal law of gravitation?

I am having trouble comprehending how anyone could come up with this formula: $$F = \frac{GMm}{d^2}.$$ Could someone walk me through this?
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2answers
36 views

How did Newton figure out the law of gravity? [duplicate]

How did Newton figure out the law of gravity? I know there are two other questions answering the same question but I did not understand anything from the answers Is there a third way of knowing how ...
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0answers
33 views

Elliptical path of planets [duplicate]

Why are the planet's orbits in the form of an ellipse and what is the proof that earth moves in an elliptical path with the sun at its foci? Initially it was thought that earth moved in a circular ...
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3answers
1k views

Are all trajectories parabolic?

I've heard this before, and it makes sense. Is it true? This being: Due to the effects of gravity and inertia, an object in movement not being acted on by any other force will form a parabolic curve ...
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3answers
128 views

How often does the earth rotate around the common center of mass with the moon?

I could not find anywhere how long does it take for the earth to rotate around the center of mass of the earth moon system, which is located inside the earth but off-center. And does this motion have ...
30
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5answers
11k views

Would you be weightless at the center of the Earth?

If you could travel to the center of the Earth (or any planet), would you be weightless there?
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2answers
40 views

If I make a object enter a planet's gravity it hits the surface with huge velocity, where is it gaining k.e. from?

If I make a object enter a planet's gravity range,it hits the surface with huge velocity,where is it gaining k.e. from? If i keep sending more and more heavy things like above and some how harness the ...
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2answers
71 views

Is it possible to apply Newton's equation of gravitation to attractive force between the moon and the ocean? [closed]

Someone was asking me how much force is acting on the waves when the moon is closest to the earth. Of course the first thing I tried to do is apply Newton's equation for universal gravitation $$F = G ...
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0answers
55 views

Sphere of electric charge revisited

I am thinking about a sphere of homogeneous charge distribution (see Electric field due to a solid sphere of charge, for example). Here we use a Gaussian surface (blue area) to find the electric ...
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0answers
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the torsion balance of the Cavendish experiment

I need to perform the Cavendish experiment and build a torsion balance but I can't find metallic spheres with enought mass so I was thinking about using a pair of dumbbells instead. My question is if ...
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2answers
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How do grandfather clocks keep going?

How do grandfather clocks keep going? The pendulum is what makes the clock go. However, the pendulum will slow down due to friction. What energy source keeps the pendulum from eventually stopping?
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2answers
54 views

Why are L4 and L5 Lagrange points stable as points and not part of a circle?

I read this Phys.SE thread which is similar Why are L4 and L5 lagrangian points stable? but I did not want to necro that thread. It seems that most discussions of a three body problem are presented ...
23
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8answers
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Why are L4 and L5 lagrangian points stable?

This diagram from wikipedia shows the gravitational potential energy of the sun-earth two body system, and demonstrates clearly the semi-stability of the L1, L2, and L3 lagrangian points. The blue ...
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3answers
256 views

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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1answer
42 views

Would the Hubble Space Telescope be of benefit for optical astronomy at Lagrangian L5 point?

The Hubble Space Telescope will enter a decaying orbit in 2024. This is a physics based question, so I don't want to get into the engineering details more than necessary. Just for background, the ...
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4answers
157 views

What is the speed of Newtonian gravity?

I already read this Phys.SE question but my question is different. I'm well aware that the effect of gravity in GR gets transmitted from point to point at the speed of light. But let's ignore GR for ...
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2answers
45 views

Gravity effect on moving bodies

If we imagine two suns of equal mass, and a small object in their combined center of gravity, which is not moving, it will stay there forever. If the object is displaced a little bit towards one of ...
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6answers
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Why don't planets have Circular orbits?

This might be a completely wrong question, but this is bothering me since many days ago. Given the mass (Sun) curves the space around it, gravitation is the result of such curved space (Correct me if ...