What is Gravitational constant: Definition and 84 Discussions

The gravitational constant (also known as the universal gravitational constant, the Newtonian constant of gravitation, or the Cavendish gravitational constant), denoted by the letter G, is an empirical physical constant involved in the calculation of gravitational effects in Sir Isaac Newton's law of universal gravitation and in Albert Einstein's general theory of relativity.
In Newton's law, it is the proportionality constant connecting the gravitational force between two bodies with the product of their masses and the inverse square of their distance. In the Einstein field equations, it quantifies the relation between the geometry of spacetime and the energy–momentum tensor (also referred to as the stress–energy tensor).
The measured value of the constant is known with some certainty to four significant digits. In SI units, its value is approximately 6.674×10−11 m3⋅kg−1⋅s−2.The modern notation of Newton's law involving G was introduced in the 1890s by C. V. Boys. The first implicit measurement with an accuracy within about 1% is attributed to Henry Cavendish in a 1798 experiment.

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  1. R

    Gravitational Constant (universal)

    I was looking at the gravitation constant and I didnt understand the parts of it with kg, and seconds. Could someone please explain in detail how to use this constant and give an example of some calculations? Thanks
  2. S

    How Can One Calculate the Gravitational Constant G by Combining Two Formulas?

    I wonderd how if could calculate G the gravitational constant by combining the two formulas; Fg=G x (m1 x m2 / r^2) Fz=m1 x g you can only make these two fromulas equal to each other when you stand on the surface of the earth. or when you recalculate your g (accelaration towards the...
  3. J

    Need help with calculating Gravitational Constant

    Homework Statement I would like some help with this question: A bomb is dropped on a foreign planet. The bomb is dropped from a height of 200m. The bomb traveled the last 100m of the fall in 2.5 seconds. What is the acceleration from the gravitational constant on this planet? 2. The...
  4. B

    Is the gravitational constant actually a variable

    Please don't be too cruel. I obviously have to be doing something wrong but it seems to me that the gravitational constant may be a variable based on coulombs constant and an objects charge per mass. The formula I have found would be G = Ke x ((Q1 / M1) x (Q2 / M2)) This would give a...
  5. K

    Gravitational Constant and Movement due to Attraction

    Homework Statement A student proposes to measure the gravitational constant G by suspending two spherical objects from the ceiling of a tall cathedral and measuring the deflection of the cables from the vertical. Draw a free-body diagram of one of the objects. If two 100.0-kg objects are...
  6. Z

    Testing for Gravitational constant

    Homework Statement A student attempts to measure the gravitational constant G by suspending two 100.0kg spherical masses from a high ceiling in a shopping center and measuring the deflection of the cables from the vertical. The cables are 45.0m long and attached to the ceiling 1.00m apart...
  7. K

    Is the Gravitational Constant a Tensor or a Constant Derived from Experiment?

    Is the gravitational constant in Newton's equations a description of the curvature of space time? if it is, does that mean it is a tensor, or simply a constant derived from experiment?
  8. B

    Exploring the Gravitational Constant: Insights from Lunar Missions

    Has the gravitational constant been measured elsewhere than Earth? Perhaps during the lunar missions? I ask this because I'm wondering whether the gravitational constant is indeed constant throughout space, or at least something that can verify that.
  9. Y

    Does the Medium Affect Gravitational Constant G?

    why does the meduim does not affects gravitational constant "G"
  10. D

    Coloumb's constant and the Gravitational constant

    I'm trying to learn more about the differences and similarities b/w electrostatics and gravitation. Ke and G seem structurally similar, but while Ke can be broken down into 1 / 4 pi Epsilon0, I was wondering if there is a similar sub-structure for G? Is there any unit in gravitation analogous to...
  11. G

    Deriving Gravitational Constant G: Pi, r, \epsilon & k Explained

    I'm just trying to find how to derive the gravitational constant G. In other words what is G in terms of pi, r, \epsilon, etc. And how does it relate to k, the permittivity of free space. Like in: Any help would be appreciated. Thanks.
  12. G

    What is the significance of the gravitational constant?

    In my physics class, we learned that everything accelerates towards each other at 6.67 x 10-11. I'm not sure what about that doesn't make sense (We didn't talk about it much, but we're expected to know about it) but something doesn't. How can EVERYTHING accelerate at the gravity? Uhhh, wouldn't...
  13. zonde

    Time dilation and gravitational constant

    I have a question about gravitational constant. Gravitational constant is dimensionfull constant but say time is is affected by gravitation causing gravitational time dilation. So the definition of second is local. Does it means that gravitational constant is well defined locally but not...
  14. C

    Understanding the Gravitational Constant: Equation, Impact, and Controversy

    I am looking for some clarification on the gravitational constant. What is the equation that produces it and what does it add to the value of a calculated gravity i.e what would the calculated gravity represent if it was removed from the equation? Also I have read it is a fudge by Newton and...
  15. U

    Schwarzschild Radius and gravitational constant

    hi, i am trying to figure out the Schwarzschild Radius of myself but i don't know how to find the gravitational constant in the equation. G=6.67 x 10-11N(M/kg)2. What do i plug in on the N(M/kg)2? is that my mass and KG? Earth's? not quite sure... please let me know. Thank you
  16. H

    Using Gravitational constant to get the final velocity

    Homework Statement Evil Alien has put an Asteroid with mass of 1,000,000kg to destroy mankind. Distance from center of the Earth to Asteroid (assume negligible center) is 10^8m and let's the gravitational force do the work. Earth radius is 6.4 x 10^6m and its mass is 5.98 x 10^24kg...
  17. S

    Does String Theory Link the Gravitational Constant to Planck's Constant?

    Hi, A few years ago, I heard that string theory suggested a link between the gravitational constant (G) and Planck's constant (h). Is this true? If so, what value of G does string theory predict? Any references would be much appreciated. Thanks, San
  18. H

    Universal gravitational constant and satellite

    A satellite is designed to orbit Earth at an altitude above it's surface that will place it in a gravitational field with a strength of 4.5N/kg a) calculate the distance above the surface of at which the satellite must orbit g= GMp/r^2 r^2 = (6.67*10^-11)(5.98*10^24)/4.5 N/kg r =...
  19. J

    Exploring the Effects of Changing Universal Gravitational Constant

    If the universal gravitational constant was changed from 6.67 X 10^-11 to 6.67 X 10^+11 what would happen? Hi. I am doing a physics project for grade 12 physics. Here is the question: The universal gravitational constant, G, is suddenly changed from 6.67 X 10^-11 Nm^2/kg^2 to 6.67 X 10^+11...
  20. B

    Is the Gravitational Constant Always Equal to 6.67*10^-11 in Newton's Law?

    I am using the Gravitational constant in "the Newton's law of universal gravitation Equation" I just want to know is the Gravitational constant always = 6.67*10^-11 Thanks so much!
  21. Q

    Exploring G: The Gravitational Constant

    G is the gravitational constant. it's approximate value is: G = (6.67428\pm0.0010)*10(power -11) m(power 3) kg(power-1) s(power-2) = (6.67428\pm0.0010)*10(power -11) N m(power 2) kg(power-2) = (6.67428\pm0.0010)*10(power -8) cm(power 3) g(power-1) s(power-2) now what is this? is this even an...
  22. T

    Solving an Equation using the Gravitational Constant

    Homework Statement Why, in the second step of the question, is 0.001 added to the right side? Part 2. In the equation Ve = sqrt 2(6.6742 x 10^-11 N m^2 / kg^2 (12.1kg))/0.106780959m I'm trying to calculate the escape velocity of an object, and have figured out everything up to this...
  23. A

    What Does Each Variable Represent in the Cavendish Experiment Equation?

    Homework Statement I'm writing a report about the gravitational constant G. I have trouble figuering out what all the variables mean means. G = w^2 * r^2 * d(Φ1 - Φ2) / 2M(1 + d/r(Φ1 - Φ2)) The experiment was executed in Cavendish torsion balance. Two wires which held 2 large orbs, and 2 small...
  24. B

    Measuring the Gravitational Constant

    A student proposes to measure the gravitational constant G by suspending two spherical objects from the ceiling of a tall cathedral and measuring the deflection of the cables from the vertical. Draw a free-body diagram of one of the objects. If two 100.0 kg objects are suspended at the lower...
  25. B

    Universal Gravitational constant

    At the Earth's surface a projectile is launched straight up at a speed of 10.1 km/s. To what height will it rise? Universal gravitational constant = 6.673e-11 N m^2/kg^2 Radius of the Earth = 6.370e+6 m Mass of the Earth = 5.980e+24 kg I know to use the equation U= - (Gm1m2)/ r but I...
  26. D

    GM - M mass of earth , G gravitational constant

    im trying to find the maximum distance of a spacecraft from the earth, whre GM is used ( M is the mass of the Earth and G is the gravitational constant) ... i was just wondering if there is a general formual for this?
  27. daniel_i_l

    Gravitational Constant: Deriving Newton's Law with a TOE

    I wasn't sure were to put this but I think that it's supposed to go here: I was in some science site and I saw one of those "prove Einstein wrong" kind of adds. Now I know that that kind of stuff is garbage but I was curious (and bored) so I went to have a look. It turnes out that there's a...
  28. W

    Gravitational Constant: What Influences Its Value?

    I'm asking myself, what influences the gravitational constant? Our universe must somehow have characteristics that have a certain mathematical relation which leads to this value... Have any papers been written on the matter?
  29. R

    The base units of the Gravitational Constant 'G'?

    Hi. Part of my homework was to work out what the SI base units of the gravitaional constant are. I'm crap at working out base units so could somebody help me out? Thanks If anyones wondering, G is 6.67 x 10ˉ¹¹ N m² kgˉ²
  30. R

    Newtons Gravitational constant?

    WHY was this thread closed? it's a perfectly legit topic and question. many people have offered an explanation for why G is what it is. it is what it is because of the units of time, length, and mass we humans have anthropocentrically decided to use. it is a fundamental quantity and if...
  31. D

    Gravitational constanT G - HELP

    gravitational constanT G -- HELP! ok, right now I'm working on a physics project :) satelite motion around earth...I managed to create a program that simulates all that stuff...but I don't quite like my G constant! In my program I want to recreate moon and Earth relationship! so...
  32. J

    What is the Plank unit explanation for the gravitational constant G?

    When I took physics I learned that cavendish measured the gravitational constant G (a so-called, “non-derivable constant”), by using a torsion balance to measure the attraction of two bodies. However, what exactly is G? Is it just there to make things "fit" or what? So some time ago I read a...
  33. holly

    Why isn't the force 1N times the gravitational constant?

    For a fabrication (*sniff*), I certainly am having trouble in a very real way. These are some upcoming test questions. I don't understand the answers. *sniff* Q. An astronaut in outer space wants to play a solitary game of "throw, bounce, catch" by tossing a ball as massive as he is against a...
  34. I

    What is the Universal Gravitational Constant?

    Can anyone give me a definition and explain why it appears in Newtons law of gravitation.
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