Gravitational field Definition and 366 Threads

The Moon's mass is 7.34x10^22 kg, and it is 3.8x10^8 m away from Earth. Earth's mass is 5.97x10^24 kg. (a) Calculate the gravitational force of attraction between Earth and the Moon. I already did that. It's 2.01e+20. (b) Find Earth's gravitational field at the Moon. This is the part I'm...

Homework Statement This is not a homework problem per se, but more of boredom, and curiosity. I was trying to calculate the gravitational field difference on a human body if it were near a black hole. Used Newtons universal law of gravitation, and such, and got my numbers. Despite the numbers...

Homework Statement Find the magnitude of the gravitational field a distance r from an infinitly long uniform thin rod whose mass per unit length is (lamda) Homework Equations The Attempt at a Solution Need some clarification really i know dgx=-Gdm/r2 r=r2-r1 lamda=m/L...

Homework Statement A square parallel plate capacitor with vertical plates of area A and distance d, charged with a constant charge Q and is completely filled with a dielectric material the same dimension as the gap between the plates, with dielectric constant k and mass m. Assuming the...

Why is there no satisfactory way to define the energy density of a gravitational field? Why must we use global energy concepts? I'm currently reading proofs of the Positive Energy Theorem, but none of the references explains why this is so. Can anyone explain it or point me to a good reference?

Homework Statement I found this statement from my book : For points outside a uniform sphere of mass M, the gravitational fields is the same as that of a point mass M at the center of the sphere. My question : what is the meaning of it? Homework Equations g=G\frac{M}{r^2} The...

I am working on some interesting topics which relate to the speed at which gravity propagates. My question is this: within the frameworks of special and general relativity (or any other widely accepted theory, for that matter), is it necessary for gravitons/gravity waves to propagate at...

When a body is fired upward with escape V (i.e 11.2 km/s) then what will be the height when the body leaves the gravitational field? I found by using formula 2gh=Vf^2 - Vi^2 keeping vf= 0 and vi=11200m/s then I got h=6400km= radius of the earth. Is it range of the gravitational field?

Two ideal gases are mixed in the box of infinite height placed in constant gravitational field. There are n_1 moles of the first gase and n_2 moles of the second. Their molar mases are M_1 and M_2 respectively. Let's assume that the temperature is constant. What's the molar concentration as...

A satellite is designed to orbit Earth at an altitude above its surface that will place it in a gravitational field with a strength of 4.5 N/kg. a) Calculate the distance above the surface of Earth at which the satellite must orbit. b) Assusming the orbit is circular, calculate the...

Homework Statement What is the magnitude of the gravitational field at the surface of a neutron star whose mass is 1.80 times the mass of the Sun and whose radius is 9.3 km? Homework Equations g = GM/r2 The Attempt at a Solution G is ofcourse 6.67x10^-11 r^2 is 8.649x10^7 m...

In Newtonian physics gravity is a force and in relativity it's curved spacetime if I understand it correctly. So my question is, does the gravitational field of an object look different to different observers? What I mean is, does one reference frame see the strength of the field to be greater...

My question is, if an object with no velocity is placed in a gravitational field, what causes it to accelerate? In Newton's theory of gravity, it was just accepted that if there is a force on an object, it accelerates. However, in general relativity, acceleration is now due to an object's...

1. Calculate the gravitational field constants for the following: Mars (r=3.43 x 10^6m , m= 6.37 x 10^23 kg) Jupiter (r= 7.18 x 10^7 , m = 1.90 x 10^27kg) Mercury (r=2.57 x 10^6m , m= 3.28 x 10^23 kg) 2. F = mg Fg = Gm1m2 r^2 3. So i tried subbing these given masses into the second...

I have this assignment in physics class and I'm stuck on this 1 question. What we were doing: We were hanging 0.10kg, 0.20kg weights etc.. on a Newton scale and we were recording the force of gravity. For 0.10kg I recorded 1 N, 0.20kg was 2 N, and so on until 1kg was 10 N. So the question...

1. A mass M is attached to a fixed spring of constant K and oscillating with an amplitude A, the spring is hung from the ceiling in a gravitational field with constant free-fall acceleration g. 2. What is the oscillation frequency? Is it affected by gravity? Mx''=-Kx-mg => ?? 3. I figured it...

Hi, Do sound waves experience a redshift similar to that of light in a gravitational field? Does anyone know the equation governing the change in frequency of the sound? Is this the same as the Doppler shift for an accelerating source of sound? Thanks.

Hello. A drop falling in air moves with terminal velocity (uniform velocity) when drag force balances its weight. But when charged droplet moves in electric field (In Millikan's Oil drop Method when there is vaccume between two plates) it is suspended between two plates when electric force...

We know that the energy density of the electric field is: \frac{1}{2}*\epsilon*E2 then, can we infer that the energy density of the gravitational field is: 1/(8\piG)*g2? Here, g is the gravitational field intensity

Homework Statement The escape velocity is the velocity of an object at the surface of a planet that would allow it to be removed completely from the planet’s gravitational field. Calculate the escape velocity for an object on the surface of Pluto. mass of Pluto: 1.3 *1022 radius of...

Homework Statement I recently had a test in the theory of relativity, and there was one task which I could not solve. This one has bothered me since the day I had the test. It was a compound task about GPS-satellites. There is no tricky calculations, or anything like that. The task aims at...

Can they exist ?? Like Magnetic Field lines and Electric Field lines

We know matter/energy creates a gravitational field. But energy can be carried away from a system of orbitting bodies in the form of gravitational waves. So if gravitational fields can carry away energy (gravitational wave), then the gravitational field has an energy density in and of itself...

Homework Statement The tallest spot on Earth is Mt. Everest. But another well-known mountain is the Mont Blanc, European Alps, which is 4807 m above sea level. If the radius of the Earth to sea level is 6367 km, how much does the gravitational field strength change between the sea level value...

Space-Time is deformed from a uniform gravitation field to one that is compressed inward so as to form a curvature. That curvature is uniform and can be understood as a series of decreasing diameters of circular field lines. If that is the case, then why are the planet's orbits elliptical and...

4. A particle is launched vertically from the surface of the earth, and rises to a height of 2RE above the surface before falling back. Ignore air resistance entirely. a) Find the initial speed of the particle. (Look up the necessary numbers.) b) This is a problem of motion in one dimension...

I posted this question in the general physics section and the physics part has been answered somewhat. However the cosmological components remain un-answered. Would someone be kind enough to comment on those aspects please? Here is the question; Matter and Antimatter, I have always...

A rocket is accelerating upwards from rest in a uniform gravitational field g. Notation: m(t) is the mass of the rocket plus remaining fuel, m0 is the initial total mass, vex is the exhaust speed (relative to the rocket), and k is the rate, in kg/s, at which fuel is consumed. By considering...

As a pendulum can be used to calculate the gravitational field strength by using the equation Time period= 2(pi) sqrt (length/g) this equation assumes that the pendulum bob is moving in Simple harmonic motion. However at very small lengths the pendulum bob tends to move in a more...

I have been trying to calculate the time it takes for an object of negligible mass to free fall towards an object with a large mass, taking into account that the gravitational acceleration experienced by the small object increases as it moves closer to the big object. The first thing I tried...

Did General Relativity predict any mass changes of objects in a strong gravitational field?

Homework Statement A 250-kg space probe weighs 935 N on the surface of Mars. What is the gravitational field strength on the surface of Mars? Homework Equations W=mg g=Gm1/r^2 Fg=Gm1m2/r^2 The Attempt at a Solution Okay, so at first I thought it would be...

Lets say I make 2-slit interf. experiment with slow (low enegry) electrons. I make their path as long as possible so they have time to fall in the Earth's gravitational field while they are flying. So electrons are attracted to the Earth, hence the Earth is attracted to the electron beam...

Homework Statement A space station consists of two living modules attached to a central hub on opposite sides of the hub by long corridors of equal length. Each living module contains N astronauts of equal mass. The mass of the space station is negligible compared to the mass of the astronauts...

Homework Statement Consider a particle of mass m constrained to move on the surface of a paraboloid whose equation (in cylindrical coordinates) is r^2=4az. If the particle is subject to a gravitational force, show that the frequency of small oscillations about a circular orbit with radius...

Homework Statement Three objects -- two of mass m and one of mass M -- are located at three corners of a square of edge length l. Find the gravitational field g at the fourth corner due to these objects. (Express your answers in terms of the edge length l, the masses m and M, and the...

The action of non-spinning particles in scalar gravity is S=-\int{\sqrt{-g}(\frac{1}{8\pi}g^{\mu\nu}\Phi_{,\mu}\Phi_{,\nu}-\rho e^{\Phi})d^4x} where \rho presents the comoving density. Now, I want to know the formula when particles with classical spin. Thank you!

Homework Statement Two identical particles, each of mass m, are located on the x-axis at x = +x0 and x = -x0. Determine a formula for the gravitational field due to these two particles for points on the y axis; that is, write \vec{g} as a function of y, m, x0, and so on. Express your...

Hello Everyone, I've been trying to get the answer to this problem for ages now and I just can't match my answer with the one in the back of the textbook. I hope you can let me know what I'm doing wrong. Homework Statement What is the gravitational field strength at a place 220 km above...

Homework Statement (a) Find the altitude above the Earth's surface where Earth's gravitational field strength would be two-thirds of its value at the surface. Assume re = 6.371 multiplied by 10^3 km. wrong check mark km (b) Find the altitude above the Earth's surface where Earth's gravitational...

Hint: Use shell theorem and/or flux argument for a symmetrical shell. A thin spherical shell has a radius of 3.4 m and a mass of 456 kg. The Universal gravitational constant is 6.6726 x 10^-11 N m^2/kg^2. What is the gravitational field 1.4 m from the center of the shell? Answers in units of...

If two objects, let's say two pool balls (or giant balls of neutronium for that matter), are placed in a closed universe that contains no other matter or energy, at rest with one another, is there a distance at which they exert absolutely no gravitational pull on each other? Or will there be...

Is holding something in a gravitational field "doing work"? My son and I are on opposite sides of this question - if I am holding something in my hand in a gravitational field, am I doing work? My position is this - if I constantly accelerate a ball in space I am doing work. Since...

I just came across this expression ds^2 = (1+gz/c^2)^2(cdt)^2 - dx^2 - dy^2 - dz^2 in entry #19 of this thread [PLAIN] https://www.physicsforums.com/showthread.php?t=227753[/URL] for the metric of a uniform gravitational field. Is this correct? I was wondering because it yields...

Astronauts in a space capsule orbiting the Earth at a height of 900km experience weightlessness: hence the gravitational field due to the Earth must be zero at that altitude'. Can someone please help ? What does it mean?

Homework Statement [FONT="Arial Black"]making the worst possible combination of errors, an oxygen atom has a charge of 3.8x10^-39C. Treating the atoms as point particles, compare eletric force of two such oxygen atoms with gravitational force between atoms. is the net force repulsive or...

Hello, Is there any empirical evidence that electromagnetic radiation produces gravitational fields? I understand that as a form of energy it is expected to induce a spacetime curvature, but has this prediction of GR actually been tested? Is it at all subject to any controversy? Thanks, Armin

A satellite orbits a planet. The gravitational field strength at the radius of the orbit is 12 N/kg. What will the gravitational field strength at the position of the satellite be if - The planet's density is doubled? - The satellite's mass is doubled? I just don't understand their...

Hello everybody! I was read in a web page that magnetic field act over the ferromagnetic objects in the same way gravitational field act over any material object, mean magnetic field is a potential field energy as gravitational field. (http://van.physics.uiuc.edu/qa/listing.php?id=432") As...

Does the velocity of light remain costant in a gravitational field? In my calculation it is less than c.