Gravitational field Definition and 372 Threads

In physics, a gravitational field is a model used to explain the influences that a massive body extends into the space around itself, producing a force on another massive body. Thus, a gravitational field is used to explain gravitational phenomena, and is measured in newtons per kilogram (N/kg). In its original concept, gravity was a force between point masses. Following Isaac Newton, Pierre-Simon Laplace attempted to model gravity as some kind of radiation field or fluid, and since the 19th century, explanations for gravity have usually been taught in terms of a field model, rather than a point attraction.
In a field model, rather than two particles attracting each other, the particles distort spacetime via their mass, and this distortion is what is perceived and measured as a "force". In such a model one states that matter moves in certain ways in response to the curvature of spacetime, and that there is either no gravitational force, or that gravity is a fictitious force.Gravity is distinguished from other forces by its obedience to the equivalence principle.

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  1. A

    Gravitational field of a moving object

    Hello, Two physics professors said two different things about the invariance of mass. One said that "mass" is a quantity which is always measured in the object rest frame - and therefore invariant to the Lorentz transformation. In additions, laws of motion in "real life" (relativistic...
  2. marcus

    Interaction of light with the quantum gravitational field

    I want to gather some links about this. If you know of some good articles and can add some links to the stash, please do. The gravitational field is the geometry of spacetime and can be roughly equated with spacetime itself, or a general idea of the vacuum----the ideas tend to overlap because...
  3. S

    ? Earth's Gravitational Field Effect on space shuttles

    ? Earth's Gravitational Field Effect on space shuttles Hi, i have a physics question in my physics portfolio, it goes as follows Critically assess the following statement: ‘Astronauts in a space capsule orbiting the Earth at a height of 900km experience weightlessness: hence the...
  4. S

    Is Earth's Gravitational Field Zero at 900km Altitude?

    ? Earth's Gravitational Field Hi, i have a physics question in my physics portfolio, it goes as follows Critically assess the following statement: ‘Astronauts in a space capsule orbiting the Earth at a height of 900km experience weightlessness: hence the gravitational field due to the Earth...
  5. 4

    What is the formula for calculating gravitational field?

    1. A person throws a ball upwards with a speed of 15 m/s, calc: a) the time to the top of the trajectory (1.53s) b) time the ball is in flight (3.06s) c) max height of the ball (11.5m) 2. An astronaut is repairing top of her craft while docked on a strange new planet. ( :rolleyes: ) She...
  6. L

    Center of gravity in a non uniform gravitational field

    Hi: I have a very big concern about my mechanics homework because a problem says: "Find a formula that gives the position of the center of gravity and make sure that in the limiting case of a uniform gravitational field your formula predicts that both center of gravity and center of mass...
  7. M

    Escape Velocity Calculation for Orbiting Satellite

    I am having some difficulty with this question: A satellite is in orbit around Earth at an altitude of 3700 km. How much must its speed increase, in km/h, to escape the Earth's force of gravity? I'm stumped. Please help
  8. G

    Gravitational field strength formula

    Q: "The Earths radius is 6700km. Show that the magnitude of the gravitational field strength at a height of 350km above the Earth's surface is about 9 N/kg" I got the mass of the Earth which is 5.98E 24 G the constant = 6.67E -11 Formula : g= GM/r² , i can't seem to get 9, am I supposed...
  9. Y

    Gravitational field, two body problem, lagrangian points

    I want to calculate the lagrangian points of the gravitational field in a 2-body problem. i want to superpose the two gravitational fields of the bodys and after that transform them into a rotating system which has the same angular velocity as the 2-body system does have. from this...
  10. U

    Solving Gravitational Field: What Did I Do Wrong?

    the question is http://home.earthlink.net/~urban-xrisis/phy.jpg g=\frac{GM}{x^2} x=\sqrt{r^2+a^2} g=\frac{GM}{(\sqrt{r^2+a^2})^2} g=\frac{GM}{r^2+a^2} since there are 2 masses... g=2 \frac{GM}{r^2+a^2} my book's answer is: g=\frac{2MGr}{(r^2+a^2)^{3/2}} what did I do wrong?
  11. A

    Gravitational field due to a cylinder

    Calculate the gravitational field due to a homogeneous cylinder at an exterior point on the axis of the cylinder. Perform the calculation by computing the force directly. I'm not sure if I did this right, here's what I did z = distance from point to center of cylinder r = distance from...
  12. T

    Does a massive object interact with its own gravitational field?

    Does an electrically charged particle's own electric field affect its own path in space? i.e., does the particle's electrical nature interact with its own field? Does a massive object interact with its own gravitational field?
  13. G

    How do you calculate time dilation in a gravitational field

    How do you calculate time dilation in a gravitational field. I already know SR time dilation equations, t=t*sqr(1-v^2/c^2), I have even designed a software in VB to calculate it. But I do not know how to calculate time dilation in General Relativity. Can someone please tell me? I am trying...
  14. A

    Two masses and a Gravitational field

    A point mass of 3.8kg is on the x-axis at x=8.2 and an equal point mass is on the y-axis at y=5.9. What is the magnitude of the gravitational field from these two masses at the origin? Well for this problem I tried using the equation F= G m1 m2/ r^2 for r I added 8.2 and 5.9 for G I...
  15. P

    Far Gravitational field of a moving mass

    I've been trying to figure this one out for a while, I could use a bit of help. I think I'm getting close. If we consider the metric (1+2*m/R)*(dx^2+dy^2+dz^2) + (-1+2*m/R) dt^2, we have the metric of the nearly-Newtonian far-field of a body with mass m. If the mass isn't moving, we...
  16. A

    Physics Help : gravitational field

    Two stars, masses 10^20kg and 2* 10^20kg respectively, rotate about their common centre of mass with an angular speed of w. Assuming that the only force on a star is the mutual gravitational force between then, calculate w. Distance = 10^6km and that G= 6.7*10^-11Nm^2/kg^2
  17. L

    Gravitational Forces on the Edge of a Disk

    What if we had a large and massive object shaped like a disc (look at the attachment) and we would walk on its edge. If we would step on the flat part what would happen? P.S. I am going on holidays for a fe days so i won't be abel to check out your answers very soon.
  18. T

    Calculate the gravitational field of a object

    how do you calculate the gravitational field of a object e.g black hole (does it refer to its density and mass?
  19. M

    Gravitational field in a hollow sphere

    Can someone please give me a qualitative justification for the gravitational field inside a uniform hollow sphere being zero? I'm having a lot of trouble understanding this. Prof. said (in class) not to worry about the higher order polynomials involved, just be concerned with it...
  20. B

    Gravitational field of globular clusters ?

    what does the gravitational field at the center of a globular cluster look like? it doesn't look as though there is any angular momentum - is there a 'center' of gravity inside? a black hole?
  21. I

    Gravitational Field Strength of Sun vs Moon at Earth

    I was just wondering. How come the gravitational field strength of the sun is much larger than the gravitational field strength of the moon at when you calculate both values at Earth's position?
  22. Z

    Geodesics inside a spinning ball of the gravitational field matter

    The linear velocity of rotation of a spinning ball of the gravitational field matter (gfm) is faster at its edge than in its central part. According to Einstein's theory of the spinning disk, the spacetime curvature at the edge of the gfm ball is larger than that in the central part; and...
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