What is Gravitational energy: Definition and 67 Discussions

Gravitational energy or gravitational potential energy is the potential energy a massive object has in relation to another massive object due to gravity. It is the potential energy associated with the gravitational field, which is released (converted into kinetic energy) when the objects fall towards each other. Gravitational potential energy increases when two objects are brought further apart.
For two pairwise interacting point particles, the gravitational potential energy



U


{\displaystyle U}
is given by




U
=




G
M
m

R


,


{\displaystyle U=-{\frac {GMm}{R}},}
where



M


{\displaystyle M}
and



m


{\displaystyle m}
are the masses of the two particles,



R


{\displaystyle R}
is the distance between them, and



G


{\displaystyle G}
is the gravitational constant.Close to the Earth's surface, the gravitational field is approximately constant, and the gravitational potential energy of an object reduces to




U
=
m
g
h


{\displaystyle U=mgh}
where



m


{\displaystyle m}
is the object's mass,



g
=
G

M

E



/


R

E


2




{\displaystyle g=GM_{\text{E}}/R_{\text{E}}^{2}}
is the gravity of Earth, and



h


{\displaystyle h}
is the height of the object's center of mass above a chosen reference level.

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  1. L

    Satellites, Orbits and Gravitational Energy

    Two satellites, A and B, both of mass m = 110 kg, move in the same circular orbit of radius r = 7.45 x 10^6 m around Earth but in opposite senses of rotation and therefore on a collision course. (a) What is the total mechanical energy EA + EB of the two satellites + Earth system before the...
  2. N

    Understanding Gravitational Energy in Motion

    I made a note of the above quote a while ago and don't recall the source. I did not understand it then and in coming across it again I still don't...Can anyone explain?? Does this not completely ignore gravitational potential energy?
  3. E

    How Much Energy Is Needed to Launch a Satellite into Orbit?

    Homework Statement How much energy is required to launch a 200 kg satellite from the surface of the Earth into a circular orbit with radius 8.0 * 10^6 m? G=6.67*10^-11 Homework Equations Ep= -GMm/r The Attempt at a Solution I calculated the gravitational potential energy of...
  4. A

    Orbiting a Star: Exploring Kinetic & Gravitational Energy

    An object orbits a star, both items comprise the system. I am looking for confirmation of a couple of concepts regarding orbits. As the object slows down, does the kinetic energy of the system decrease, and does the total energy of the system decrease? As the kinetic energy of the system...
  5. S

    Calculating Speed from a Falling Ball's Gravitational Energy

    Homework Statement How far would a 1.00 Kg ball have to fall freely to reach a speed of 100 Km/h ? Homework Equations \Delta E_g = \Delta E_k The Attempt at a Solution \Delta E_g = \Delta E_k i then expanded to: mgh' - mgh = \frac{1}{2}m(v')^2 - \frac{1}{2}mv^2 i...
  6. R

    How Is a Skier's Gravitational Potential Energy Affected by a Mountain Lift?

    Homework Statement A 70.0 kg skier rides a 2700 m long lift to the top of a mountain. The lift makes an angle of 14.3° with the horizontal. What is the change in the skier's gravitational potential energy? Homework Equations The Attempt at a Solution mg cos(?) * (h0 - hf)...
  7. N

    Gravitational energy : positive or negative ?

    I know that gravitational energy is a delicate topic in GR. It is true that the localisation of gravitational energy is not possible in GR but it should at least be possible to determine correctly the sign of the gravitational energy. I found the following article in arxiv.org, nl...
  8. J

    General Potential Gravitational Energy

    I was just wondering if there were any applications of the equations U= GMm/r. Which basically means we are not to involve anything on Earth's surface. Thx
  9. M

    Kinetic and gravitational energy

    Q: An object at a height of 15 m above the ground is traveling at 25m/s. Find its a) kinetic energy b) gravitational energy If I find out how to do (a), I am sure I will figure out B. The problem is I don't know how to figure out (a) I know that Kinetic Energy = 1/2 mass (speed)^2...
  10. U

    Gravitational Energy Transfer: Exploring the Interaction of Bodies

    Let's see if I can articulate this question the way that I'm thinking about it... Imagine you have a big star (like the sun)... and every so often a comet or meteor (or even several of them) whiz past. My understanding is that the star's gravity will influence the path of the comets and/or...
  11. S

    Calculate Gravitational Self-Energy of the Sun

    Calculate the gravitational self energy of the sun (without using numbers) Textbook says that this is the nergy needed to take every particle from the sun's surface to infinity there are an infinite number of particles on the sun ... would there be some sort of integral that relates the...
  12. B

    Gravitational Energy: Why Negative?

    I remember that someone (maybe Hawking) said the total energy of cosmology is zero: the matter hold the positive energy and gravational field possesses the negative energy. But I can't understand it, why the gravational field's energy is negative? As far as I understood, from the view of gauge...
  13. wolram

    Formula for gravitational energy

    i have looked on the net for a formula that would give me an idea of how much gravitational energy verses other energies is given of when a massive body is destroyed, is there such a formula? or is it just that the mass of the body is converted into energy by E=M^2 and the gravitational...
  14. denian

    Change in gravitational energy

    here's a question. a body of mass m at a surface of the Earth is brought to a point a distance 2R ( R = radius of the Earth ) from the centre of the Earth. what is the change in gravitational energy of the body. will the gravitational energy of the body increased or decreased?
  15. M

    Gravitational Energy: Is it Really Zero?

    is it not true that the total energy of the universe is zero? i heard somewhere that the gravitational attraction between objects is exactly canceled by the electromagnic force required to keep them apart at close ranges. this might only mean gravitational energy is zero. but gravity still is...
  16. J

    Why Is Gravitational Energy Considered Negative?

    What is meant by the theory/fact that gravitational energy is negative? I would have thought that this would mean that gravity would cause objects to be repeled from each other
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