What is Gravitational attraction: Definition and 68 Discussions

Gravity (from Latin gravitas 'weight'), or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are attracted to (or gravitate toward) one another. On Earth, gravity gives weight to physical objects, and the Moon's gravity causes the ocean tides. The gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing and forming stars and caused the stars to group together into galaxies, so gravity is responsible for many of the large-scale structures in the Universe. Gravity has an infinite range, although its effects become weaker as objects get further away.
Gravity is most accurately described by the general theory of relativity (proposed by Albert Einstein in 1915), which describes gravity not as a force, but as a consequence of masses moving along geodesic lines in a curved spacetime caused by the uneven distribution of mass. The most extreme example of this curvature of spacetime is a black hole, from which nothing—not even light—can escape once past the black hole's event horizon. However, for most applications, gravity is well approximated by Newton's law of universal gravitation, which describes gravity as a force causing any two bodies to be attracted toward each other, with magnitude proportional to the product of their masses and inversely proportional to the square of the distance between them.
Gravity is the weakest of the four fundamental interactions of physics, approximately 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a consequence, it has no significant influence at the level of subatomic particles. In contrast, it is the dominant interaction at the macroscopic scale, and is the cause of the formation, shape and trajectory (orbit) of astronomical bodies.
Current models of particle physics imply that the earliest instance of gravity in the Universe, possibly in the form of quantum gravity, supergravity or a gravitational singularity, along with ordinary space and time, developed during the Planck epoch (up to 10−43 seconds after the birth of the Universe), possibly from a primeval state, such as a false vacuum, quantum vacuum or virtual particle, in a currently unknown manner. Attempts to develop a theory of gravity consistent with quantum mechanics, a quantum gravity theory, which would allow gravity to be united in a common mathematical framework (a theory of everything) with the other three fundamental interactions of physics, are a current area of research.

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  1. Sam Jelly

    Proving the gravitational force of a solid sphere using integration

    This is my attempt at the solution. x from the equation dF = GmdM/x^2 represents the distance between the circular plate’s center of mass and mass m.
  2. J

    Masses colliding due to gravitational attraction

    When one mass is held fixed, the other mass acquires a speed v from gravity. I don't understand the following explanation: When both masses can move, they share the kinetic energy, so both have speed v/√2, so the relative speed is √2v. Hence to collapse the same distance r, the latter case will...
  3. L

    B Why are gravitons needed to explain gravitational attraction?

    Hi! Isn't gravity just a smaller object moving toward the lower energy state created by a larger object (time slows down the closer you are to a massive object)? Why do we need a force carrying particle for gravity?
  4. G

    B Analogies for Gravitational Attraction in Physics

    I am thinking of the mechanism that causes mass-energy to curve spacetime We have the Wheeler (was it ?)description, viz approx "mass tells spacetime how to curve and spacetime tells matter how to move...". Are there any analogous circumstances in other areas of physics where all (or a...
  5. Lars1408

    I Why Do Objects Fall Along Spacetime Ripples?

    When people try to explain how gravity works, the following example is constantly used . However, I don’t understand how this explains HOW gravity works. By using this example, gravity itself is used as a bias to explain how gravity works. How can explain gravity by saying “things fall along...
  6. John10086

    Irodov problem 1.12 — A 3-body gravitational attraction problem

    The thing is, I've already looked up at the solution online at it's t= 2a/3v. But I've approached it a different way and I can't really tell what I'm doing wrong, my solutions gives out t= (a/√3v )* (π/3),I don't know what's wrong with it. Here's my approach: The points will meet at the...
  7. A

    B Understanding gravity: mass and gravity relation

    << Mentor Note -- thread moved from the Introductions forum to the technical forums >> Hello there, This is my first post, I find myself often wondering about the universe and how it works, and there are a couple of things I just can't wrap my head around. According to wikipedia the force that...
  8. I

    How long does it take for gravitational effects to work?

    Imagine a ball being tossed into 'the air'. At its peak, the ball has a velocity of 0(m/s), but how long does it actually have this velocity for? --> Neglecting the effects of air-resistance. Obviously the ball undergoes constant 'g' the whole time, but the answer to my question doesn't relate...
  9. D

    B Gravitational attraction of 2 equal masses

    Hi. If 2 equal masses are placed at rest ( an arbitrary distance apart ) on a horizontal friction-less surface do they accelerate from rest towards each other until they collide ? Thanks
  10. M

    Variation of gravitational attraction between Sun and Earth

    Homework Statement Distance Earth-Sun at perihelion = 1.471×108 km Distance Earth-Sun at aphelion = 1.521×108 km Sun mass = 2.0×1030 kg Earth mass = 5.972×1024 kg G = 6.67×10-11 m3/kg⋅s What is the change in Newton of the attraction force between the Sun and the Earth from the perihelion to the...
  11. S

    I Restricted three body problem (numerical simulation of gravitational attraction)

    Hello! I am implementing the three body restricted problem numerically (2 of them are massive and the 3rd one is not affecting them, so it is just moving in the potential created by them). I implemented it and if I put the 3rd one close to one of the big ones it moves in circles around it, while...
  12. W

    B About gravitational attraction

    say i were standing next to something very massive, like a battleship in drydock, and i were to hold a feather (not massive) very close to it. Would i witness any gravitational attraction between the feather and the ship? If not, why not? What if i did the same with a single filament of spider...
  13. K

    B Gravitational attraction between two masses

    hi I'm writing a javascript application to illustrate gravitational attraction between masses, but am getting hung up on some of the details, particularly mow far masses move in response to each other's gravitation. I've read all available wikipedia articles on gravity and have come up with...
  14. T

    Gravitational attraction of plumbline

    Homework Statement By what angle, in seconds of arc, will a plumbline be pulled out of its normal vertical direction by the gravitation attraction of a 10-ton that parks 20 ft away? Do you think that this effect could be detected? Homework Equations I think (G*m1*m2)/r^2 The Attempt at a...
  15. D

    Gravitational attraction between two atoms

    The question: Is there a gravitational attraction between two atoms if they are located at a distance of several light years of each other? Or physics does not have the answer to this question yet? ) (Sorry if this question has already been discussed on the forum. Please send a link to the topic...
  16. M.Decart

    How did Newton answer this question? (mutual gravitational attraction)

    I didn't study physics in college nor any other science major, but I love physics and read a lot about it. Still I find troubling contradictions in my understanding of Newton's interpretation of gravity. For starters, how can the force of gravity be directly proportional to the two masses? If...
  17. J

    Velocity of two spheres under gravitational attraction

    Homework Statement Two solid copper spheres of radii 1 and 2 cm are released from rest in free space, their centers being 20 cm apart. Estimate the velocity with which they collide Homework Equations density =mass/volume F=GMm/r^2 The Attempt at a Solution Find mass of each from density of...
  18. W

    Gravitational attraction thought experiment

    Hi all. New to physics forum and glad to be here. I have been referencing the site for a while now and have finally come up with a question i haven't been able to find on here. So I guess i thank all of you who are already on here for the help. Assumptions: -Imagine an infinitely...
  19. R

    Question about gravitational attraction

    So the formula is F=Gm1m2/r^2. Could you substitute one of the mass values for an energy value since gravity attracts energy ? Or would this require a different equation?
  20. V

    Gravitational attraction on the cosmic scale?

    Hi, the following two views appear inconsistent to me: In the infinite perfectly homogeneous universe: a) the net force of gravity is zero everywhere, so no energy is being exchanged and no particle is pulled in any direction whatsoever. b) the net force of gravity within a spherical...
  21. W

    Gravitation - gravitational attraction due to a nearby mountain range

    Homework Statement The gravitational attraction due to a nearby mountain range might be expected to cause a plumb bob to hang at an angle slightly different from the vertical. If a mountain range could be represented by an infinite half-cylinder of radius a and density ρ lying on a flat plane...
  22. E

    Gravitational Attraction, Electromagnetic Radiation and Dark Matter

    Since we can observe gravitational lensing and conclude that mass can affect the path of EM radiation it seems logical to me to assume that EM radiation will exert a slight gravitational attraction of it's own on a mass,- although I do not recall ever reading about this. Presumably the...
  23. S

    Gravitational Attraction: Does Smaller Mass Disappear?

    Hello, comparing the formula of gravitational attraction with F = m*a you get that the smaller mass disappear. I don't think this is physically correct, do you ? thank you
  24. P

    Gravitational attraction question

    Homework Statement two point masses (400 kg) are 10^14 m apart in deep space under no gravitational attraction besides each others. find their velocity when they are 1000 m apart.Homework Equations -G (m_1m_2)/r^2=F The Attempt at a Solution I integrated the equation above plugging in the 400...
  25. O

    Gravitational attraction of a hemisphere at its pole

    Find the gravitational attraction of a solid hemisphere of radius a anddensity1 on a unit point mass placed at its pole. My attempt: Obviously I figured that spherical coordinates would work nicely for this problem. I decided to invert the hemisphere thus placing the pole on the origin...
  26. Z

    Gravitational Attraction & Conservation of Energy

    I would like to better understand the nature of gravitational attraction and the law of conservation of energy. Imagine you measure inertial mass (using inertial ballance) of an object far from a gravitating mass which is at rest relative to the object. Then you release the object and let it...
  27. A

    Work of gravitational attraction based on height

    Homework Statement i need to find the work of gravitational attraction based on heights of balls being shot into the air. the mass of the ball is 24 grams, the height is 27cm at 0 degrees, 38 at 30 degrees, 50 at 45 degrees, 61 at 60 degrees, 80 at 90 degrees. i also need to find the initial...
  28. R

    Gravitational attraction force b/w point mass and rod

    I was wondering about a scenario where we have a unit mass M1 and a thin rod of mass M2 of length L with a distance r between them attracting each other . Is my following approach to the problem correct ??! let s = r + L I know that F= -(GM1M2)/(s^2) where G is gravitation constant therefore...
  29. K

    Simple gravitational attraction forces problem

    Each mass in the figure below is 2.00. Find the magnitude of the net gravitational force on mass A due to the other masses in figure b (the square). Figure: http://i.imgur.com/fjSgU.jpg attempt: i used the formula F=G [(m1*m2)/r^2]. all of the forces are in the direction of D so i...
  30. M

    Understanding gravitational attraction

    The book says..bodies experience mutual gravitational attraction with each particle of the earth... In the picture... the vector from the apple pointing to the center of the earth.. is that the attractive force of by the Earth attracting the apple? and what about the vector pointing from...
  31. J

    Help with a Gravitational Attraction problem

    Homework Statement Two asteroids of 1.0x107kg and 6.0x107kg respectively, are initially at rest in interstellar space separated by a large distance. Thier mutual gravitational attraction then causes then to fall toward each other on a straight line. Assume the asteroids are spheres of radius...
  32. A

    Gravitational attraction of a cone

    Hello everyone, I have been stuck on this geophysics question I have for one of my classes and I really need some help with it. Can anyone solve this question. If you do, please show me how because I am really stuck here. I am stuck on both a and b. Click the link below to see the question...
  33. B

    Gravitational attraction of a spherically symmetrical mass

    Many sources on basic gravity, like this quote from Wikipedia, say: “In the case of a spherically symmetric mass distribution we can conclude (by using a spherical Gaussian surface) that the field strength at a distance r from the center is inward with a magnitude of G/ r^2 times only the...
  34. G

    Gravitational Attraction of a Massive Particle

    I was wondering what equations govern calculating the gravitation attraction of a massive particle (say a proton) traveling at near light speed? Thanks!
  35. MikeGomez

    Does the redshift effect contribute to gravitational attraction?

    We can imagine a sphere floating freely in space. Perhaps it is something like a ping pong ball. We attach a piece of string to a random position on the surface of the sphere. If we vibrate the string, the sphere will be pulled in the direction of the string. If we repeatedly move the...
  36. D

    How Strong is the Gravitational Pull Between Two Students?

    Homework Statement what is the gravitational attraction between two students with masses of 70 kg and 50 kg, if they are 1.5 m apart? Homework Equations Fg=Gm1m2/r^2 The Attempt at a Solution so my Fg is 6.67 x 10^-11, m1 is 70 kg and m2 is 50 kg. for my radius, do i just use the 1.5...
  37. C

    Is gravitational attraction finite?

    Is there a distance where the curvature in spacetime created by an object's mass ends? Is it a finite gravity well or does the curvature just get infinitely weaker?
  38. M

    Gravitational Attraction: Could Dark Matter be Explained?

    Could the effect of "Dark Matter" be explained if in the formaul for Gravitational attraction: F = GMm/d^x Where x is considered 2 is wee bit less (may be 1.98 or some thing)
  39. K

    Gravitational Attraction of Motionless Masses

    Assuming a universe with only space and two motionless masses, would the two masses start to move toward each other?
  40. Z

    Will Two Identical Spherical Cavities in Free Space Attract or Repel Each Other?

    Suppose that in free space , dust particles are evenly distributed all around. Amidst the dust particles , there are two identical spherical cavities at some distance from each other. Do you think they will attract each other or repel or just be as they were??
  41. L

    Trying to figure out gravitational attraction between two objects.

    Trying to figure out the gravitational attraction between two objects using Newton's Law of Universal Gravity.Need to figure out what the force is.Here is a model.If anything is in ordinary parentheses then it is an exponent. ----------------------G --------____________|_____________400x300...
  42. W

    Gravitational Attraction Question

    [b]1. The mass of the Moon is 7.35x10^22 kg. At some point between Earth and the Moon, the force of Earth's gravitational attraction on an object is canceled by the Moon's force of gravitational attraction. If the distance between Earth and the Moon (centre to centre) is 3.84x10^5 km, calculate...
  43. Z

    Calculate Where Earth & Moon's Gravitational Attraction Is Canceled

    Homework Statement The mass of the Moon is 7.36 x 10 ^ 22 kg. At some point between Earth and the Moon, the force of Earth's gravitational attraction on an object is canceled by the Moon's force of gravitational attraction. If the distance between Earth and the Moon (center to center) is 3.84...
  44. H

    The Effects of Relativistic Mass on Gravitational Attraction

    2 particles are moving very fast in an "inertial reference frame." What is the force of gravitational attraction between them? Note that at low speeds it is G(m1)(m2)/r^2. Also note that the two particles are not aware of the inertial reference frame with respect to which they are moving very...
  45. P

    Calculating Gravitational Attraction Between Two Masses in Empty Space

    I'm just curious how long it would take for two 1kg masses separated by 1m to attract each other gravitationally in empty space. The formula for gravitational force is: F_{g} = G \frac{m_{1}m_{2}}{r^{2}} where r is the distance between the two masses. So if the midpoint for the two...
  46. L

    Gravitational attraction between 3 masses.

    Homework Statement A small mass M and a small mass 3M are 3.60m apart. Where should you put a third small mass so that the net gravitational force on it due to the other two masses is zero?(From mass M) Homework Equations F = G(m1)(m2)/d^2 The Attempt at a Solution I envisioned...
  47. T

    Where Is the Neutral Point Between Earth and Moon's Gravitational Forces?

    Homework Statement The mass of the Moon is 7.35x10^22 kg. At some point between Earth and the Moon, the force of Earth's gravitational attraction on an object is canceled by the Moon's force of gravitational attraction. If the distance between Earth and the Mon (centre to centre) is 3.84x10^5...
  48. H

    Where Will Earth and Moon's Gravitational Forces Cancel Each Other?

    The mass of the moon is 7.35*10^22Kg. At some point between Earth and the moon, the force of Earth's gravitational attraction on an object is canceled by the moon's force of gravitational attraction. If the distance between Earth and the moon (centre to centre) is 3.84*10^5 Km, calculate where...
  49. T

    Where will the forces of Earth and Moon cancel out?

    Homework Statement The mass of the moon is 7.35x10^22 kg. At some point between Earth and the Moon, the force of Earth's gravitational attraction on an object is canceled by the Moon's force of gravitational attraction. If the distance between Earth and the Moon (centre to centre) is...
  50. B

    How Close Do Two 100kg Spheres Hang When Suspended 1m Apart?

    Gravitational Attraction-Please Help! Homework Statement Two 100kg lead sphers are suspended from 100m long massless cables. The tops of the cables have been anchored 1 m apart. What is the distance between the center of the spheres? Homework Equations Fg= Gm1m2/r^2 The Attempt at...