Gravitational field Definition and 372 Threads

Homework Statement We have an ideal gas consisted of N classical particles, each having mass m. The system is inside a spherical bottle of radius R and is inside the gravitational field of the earth. The system is also in thermal equilibrium with a heat reservoir which has temperature T. I...

Homework Statement Taking the equation of motion for a rocket launched from rest in a gravitational field g, m\dot{v} = -\dot{m}v_{ex} - mg , and knowing that the rocket ejects mass (fuel) at a constant rate \dot{m} = -k (where k is a positive constant), so that m = m_{o} - kt . Solve...

Homework Statement This is supposed to be a simple problem that shows that light bends or gets pulled in a gravitational field. A light pulse emitted in the positive x direction travels 10 s in a uniform gravitational field of 100 m/s^2. the gravitational field points in the negative y...

gravitational field strength problem-urgent help needed Homework Statement Moon has a radius of 1740km, Mass of 7.35 x10^ 22kg, grav field strength of moon= 1.62Nkg^-1, distance from Earth to Moon is 380000km G=6.67x10^-11Nm^2kg^-2 The Moon's gravitational pull on the Earth causes the...

Is the size of Earth's gravitational field the same size as it's electric/magnetic field? Also, what is the standard theory as to why the Earth has a magnetic field? What I mean is, how is it generated? Is it the result of the Earth traveling through space and interacting with the rays etc...

Homework Statement Homework Equations The Attempt at a Solution But as you can see, when I typed the answer on the answer column, the computer marked it as wrong. Please point out my mistake in 24 hours. Thank you.

So I'm sitting here, reading about different ways to create gravitational fields as well as messing around with random thoughts and ideas, and this question comes to mind: Would greater electricity affect a gravitational field created by an electromagnet? Anyone who knows? I'd really like to...

Homework Statement Please see P2 in http://panda.unm.edu/pandaweb/graduate/prelims/SM_S09.pdf "Starting with \mathbb{Z} (z_1,z_2) above, derive expressions for the gas pressure..." Homework Equations The Attempt at a Solution To find the pressure at the top and the bottom of...

is gravitational field made with any particles

hi does anybody of you know if there is an equation that describes an atom in a gravitational field of a star or something like that (general relativity or Newton)or do you know some results that could tell me something about the magnitude of this energy corrections? do you know a method...

i am new to GTR. Mytext book use an example to show ligt bendinf. when a light release from the back of the rocket which goes around the earth, since the rocket is in free fall, light would not bent relative to the rocket, but bent relative to earth. my problem is, is that means the amount...

Consider a photon moving in same direction with a gravitational field . So the speed of photon must become greater than speed of light. how its possible ? please answer this then I'll ask my next questions. :smile:

Hello, I just read a book reagarding Newton and his laws and had few questions about it. What is Gravitational field strength exactly and what is Newton's universal gravitational constant? Aren't they the same thing? please explain these two concepts simple enough for me to understand and to...

When an object (say a ball) is pulled some distance away from another object (say the Earth) against the objects' mutual gravitational attraction, does the mass of each object decrease? (Assume that the energy expended in moving the Earth and ball away from each other comes from within the...

We had a physics lesson today on nuclear binding energy, where we looked at the mass of two protons and two neutrons independently and compared it with the mass of a helium nuclei, and were told how the discrepancy related to the release of energy during nuclear fusion. The first question in...

He who calls himself "Nabeshin" stated: "It seems to me the distinction can be best seen in the following: Differential geometry is mathematics, and this will tell us what the geodesics on a given manifold are. So if we're just finding geodesics on manifolds, maybe it's the manifold...

This is something I've always wondered... Einstein's equivalence principle says that you can't tell the difference between being accelerated in an elevator, or being in a gravitational field. No matter what, there's no mechanical device you can build, etc. But, what about 'gravitons'...

Hello, I'm trying to solve the rocket equation in a nonuniform gravitational field. The standard rocket equation at a distance x from the center of a planet of mass M gives: m*d^2x/dt^2 + v_e*dm/dt = -GmM/x^2 where v_e is the relative exhaust velocity. Multiplying by dx/dt and assuming...

A friend of mine told me he fielded this at an oral exam: "Compute the classical action S for a particle of mass m in a gravitational field U = -\alpha/r." I know the formula for the classical action is given by S = \int_{t_i}^{t_f} L(q,\dot q,t) dt, and that for a particle in a...

Homework Statement what is the gravitational field intensity at the center of the earth Homework Equations The Attempt at a Solution i was told that it was zero because you have the Earth's mass surrounding it, and graivty moves to the center of its mass (center of radius)...

Homework Statement For an ideal Bose gas in a uniform gravitational field, at what temperature does Bose-Einstein condensation set in. Gas is in a container of height L.Homework Equations Normal BEC temperature of an ideal Bose gas not under the influence of gravity is T = \frac{h^2}{2 \pi m...

How are the numerical values of gravitational field strength and acceleration due to gravity on Mars related?

1. Three objects of equal mass are located at three corners of a square of edge length d. Find the magnitude and direction of the gravitational field at the fourth corner due to these objects. (Use the following as necessary: G, d, and m.) 2. Homework Equations : g = Gm/r2 3. My attempt...

Consider the above rotating vertically aligned cylinder in Schwarzschild geometry. Would anyone agree or disagree with the following analysis? If a local observer at the highest end of the cylinder measures that end of the cylinder to be (say) 2 rpm, then another local observer will measure...

**!xxx Trajectory in a gravitational field Assume an object comes from infinity and passes by the sun at 2 solar radiuses from its center. Can you derive an equation describing the objects path using only escape velocities and C??

Here is Max Born explaining the crash of a train, in which the train is regarded to be at rest: There are two peculiar features of this gravitational field: 1. Causation. The field appears coincidentally with the collision of the train with an obstacle. If a passenger had pulled the...

Homework Statement if a proton and a electron put in a gravitational field, what is their ratio compare to one another? Homework Equations fg= GMm/r^2 mass of a proton = 1.67 x 10^-27 kg mass of a electron= 9.11 x 10^-31 kg The Attempt at a Solution i tried to divided them out, i...

Homework Statement Suppose that one is given a lump of clay of total mass M and constant density. Let P denote a particular point in space. In what way should one shape and position the clay so that the gravitational field in point P is maximum possible? It is assumed that the clay stays in...

Does a photon gain speed if it travels in "free-fall" toward the earth? A particle of mass gains speed as it free-falls to the earth, and yet, mass is just another form of energy. Light is energy. So, does light gain speed?

As a homework question, it asks, "...if the Earth were rotating so fast that the objects at the equator were apparently weightless?" Somewhere, someone said that, quote: In order for the rotation of the Earth to cancel weight, the gravitational field strength should equal the centripetal...

Homework Statement A nonuniform thin rod of length L lies on the x axis. One end of the rod is at the origin, and the other end is at x = L. The rod's mass per unit length λ varies as λ = Cx, where C is a constant. (Thus, an element of the rod has mass dm = λdx.) Determine the gravitational...

Homework Statement I am trying to get an equation of motion for the following (seemingly simple) setup. You place on a rod on a pivot. The rod's centre of mass is precisely over the pivot. Think of balancing a ruler horizontally on your finger. Gravity, of course acts downward. The...

Homework Statement A biologist studying plant growth and wants to stimulate a gravitational field stronger than the Earth's. She places the plants on a horizontal rotating table in her laboratory (on Earth) at a distance of 42.3 cm from the axis of rotation. What angular speed will give the...

For many years, i have struggled with the concept of a "field", and i basically simply have no idea what a field is or how it operates, whether it is a magnetic field, gravitational field or other. when you think of a gravitational field, as per GR, you think of "curved spacetime", but what...

Homework Statement Write an expression for the gravitational field strength E at a point distance r from a planet of mass M. (In my diagram, there are two planets with mass, m and distance 2a apart) Homework Equations The Attempt at a Solution The resultant gravitational field...

Homework Statement Considering only the gravitational fields of the Earth and the Moon, find the distance from the Earth at which a space capsule traveling between the Earth and the Moon is subject to zero gravitational force. Mass of the Earth = 5.98 x 1024kg Mass of the Moon = 7.35 x...

I've been told this is a differential equation, but I have no knowledge of the subject, so I'm hoping it is and that an answer can be found in this forum. The two equations x=1/2at2 and a=gm/r2, when r is replaced with (r0-x), with r0 being the initial radius from the mass from which the...

I've been trying to figure this out for a while, since my first semester of physics ended. It's not a homework problem, just something I've been doing for fun. I've spoken with a few people about it and they all say it's just a diff. equation but they can't remember how to solve it, and...

If photons don't have mass, why do their paths "bend" in a gravitational field? This is question #8 in the FAQ and the answer provided is this: I'm trying to understand the last sentence. I must be having a mental block: why would thinking of "relativistic mass" cause identical...

Anyone know what causes the weak gravitation field at the bottom of India / Indian Ocean (see link below)? Thanks http://news.bbc.co.uk/2/hi/science/nature/8767763.stm

1. How would clock in isotropic gravitational field, for example at centre of earth, tick compared to the clock at surface of earth? 2. How would clock in the center of Earth tick compared to the clock at center of sun?

I have read the papers of Verlinde, Jacobson, Beckenstein, Smoot and many other. They use the Unruh vacuum. It seems that Unruh vacuum is nothing but a thermal vacuum in the sense of thermodynamics. It contains vacuum fluctuations creating the virtual particle-antiparticle pairs. Verlinde wrote...

The speed of light in a gravitational field is not a scalar quantity because at any given coordinate its speed is a function of its direction. Does general relativity treat time in a gravitational field as a scalar quantity?

What quantity has the same numerical value as the gravitational field strength, but is expressed in a different unit? g= 9.8 N/kg i can't think of anything else that's 9.8 besides g

Homework Statement An astronaut arrives at a new planet, and gets out his simple device to determine the gravitational acceleration there. Prior to this arrival, he noted that the radius of the planet was 7040 km. If his 0.400-m-long pendulum has a period of 1.0 s, what is the mass of the...

This scenerio originated from https://www.physicsforums.com/showthread.php?t=391796 where is was intended to argue that in the weak field limit where Newtonian gravity is a good approximation gravitational mass is gamma*m0=E/c2, as opposed to the rest mass argued for by several in that...

I have always thought that GR was identical to classical physics in the Newtonian limit. In the Newtonian limit one can define an energy density for a gravitational field parallel to the methods used to derive the energy density of a static electric field, resulting in a formula energy...

Where on an imaginary gravitational field line between Earth and moon, a mass would have no weight neither due Earth nor due to moon?

Homework Statement 2 masses, 5k and 10kg are fixed in place at the coordinates 1,0 and 1,1 respectively. what combined gravitational field strength do they produce at the point 0,0? Homework Equations g = GM/r^2 The Attempt at a Solution total g = G(5)/(1)^2 +G(5)/2 not the right answer...

This figure is captured from my physics textbook and it is about the gravity at latitude http://pix.gogobox.com.tw/out.php?i=567045_.JPG I want to know the difference between mg0 and mg(theta). Which one is the weight of the object? Thank you!