Gravitation Definition and 918 Threads

Homework Statement http://[url=http://postimg.org/image/f7e6kp0xv/][PLAIN]http://s21.postimg.org/f7e6kp0xv/image.jpg Homework Equations Kepler's laws The Attempt at a Solution I thought the answer will be C : I and II But the solution written (it was my friends book) is B, which is correct?

If a black hole had a mass similar to the Sun (I know black holes tend to be at least three times larger but let's assume an unusual series of events) how far would the are of extremely distorted bent gravity around it be could it cause closely orbiting bodies to be pulled or pushed out of orbit...

Homework Statement http://prntscr.com/9huihp Given, Mass of the Earth = 6*1024 Mass of Satellite = 45 kg Radius of Satellite's orbit = 4.2*107 G = 6.67*10-11 Find the velocity of the satellite. Homework Equations Gravitational Force Fg = (G*Me*Ms)/(Rs2) Newton's second law: Fg = Ms*a where a...

I recently got my hands on a copy of Gravitation by John Wheeler, Kip Thorn and Charles Misner. Reading the first few pages are very discouraging. The limit of my physics knowledge are from taking high school physics. What book would give me the knowledge I need to read Gravitation?

What is the physics behind a orbit a cube planet. Does the convential physics including keplars laws and circular motion still apply. Also The cube having a centre of mass posited in the middle of the cude does this mean it can be consider point mass and the same as spherical planet orbit? any...

Homework Statement If a satellite is in a sufficiently low orbit, it will encounter air drag from the Earth's atmosphere. Since air drag does negative work (the force of air drag is directed opposite the motion), the mechanical energy will decrease. If E decreases (becomes more negative), the...

Homework Statement If two satellites A and B are orbiting the Earth out of which A is closer to the Earth then the total energy of which Earth plus satellite system is lesser?Homework EquationsThe Attempt at a Solution Should I consider only the magnitude while comparing using the formula total...

Two satellites A and B move around Earth in a circular orbit. The mass of B is twice the mass of A then I agree that kinetic energy of B is greater than that of A. But what I couldn't understand was that why are speeds of A and B equal as given in the book. Shouldn't they differ according to the...

Hello, in nuclear physics we have a mass defect by the binding energy of the nuclides. A similar effect appears in the theory of gravitation induced by the gravitational binding energy, which reduces the mass. But for example at the ISCO of an Kerr black hole we have binding energys about...

Question: There is a large parallel beam of incoming particles with mass m and uniform velocity v0 (v0≪c) in the presence of a gravitational field of a (spherical) planet with mass M and radius R. (without GR) The question is what fraction of the particles will eventually arrive at the planet...

Could there perhaps ever be floating cities? If we could get the type of technology that sends rockets into space, and have the boosters running at a constant and equal velocity inversely, could this cause anything to levitate? If so, would this even be habitable? Considering that the fumes...

In my calculus textbook (section on vector calc) it is showing that the gravitational field is conservative. I followed fine except for the first part, defining the scalar function f. Showing the field is conservative went something like this: f(x,y,z) = MM'G/\sqrt{x^2+y^2+z^2}...

Hello guys! I hope you can give me a hand with this one Homework Statement A satellite consisting of two masses attached by a rigid-massless rod of length L, are orbiting around the Earth at a distance R from the centre of the earth. During the entire movement the rod stays oriented in the...

So light has momentum: \vec p_{light} If Universal Gravitation tells us: \vec F = \frac{Gm_1m_2}{r^2} How do we get the force on light from the more massive object?... How do we know how much light will be shifted?

What happens to a body experiencing a gravitational wave? Suppose I put a ball in the path of a GR wave. As the wave passes through it, the space will expand and contract. This means that the space between every point in the ball should expand and contract. But what will be the reference point I...

Hey guys! What would be the gravitational effect of Earth on it's surface, if somehow the density of mass was uniform and equal to 2/5 of the real value? Assuming that the size e shape os the planet doesn't change.

Hi guys! What would happen to objects on the Earth's surface if it SLOWLY stopped spinning and Earth's gravitational field was kept as always. Thx

Homework Statement Hi! I would need a little help with the following problem: We have found a new planet with density ρ and radius R, and drill a hole to its center. Then accidentally, one person falls into the hole. What is his velocity when reaching the bottom (the center of the planet)...

Homework Statement IF D = 1954 meters and d = -92 meters, to the nearest MN what is the magnitude of the force on the space ship Homework Equations F=(Gmass) / r^2 F=(G x mass asteroid) / (D/2)^2 ΣFx= F asteroidright - F asteroidleft = ma The Attempt at a Solution F asteroid right = F...

I would like to make a pendulum go on moving by a permanent magnet that pushes the pendulum back with a force that is big enough to make it swing back with the same height. Can anyone tell me how much energy could be generated by a pendulum with height is 2 meter and 60 kg, swinging 90 degrees...

Newton's equation is F= G(m1•m2)/r squared What is this equation to the subject of m1, please? Thank you very much for your help!

Homework Statement At a latitude of 50° north a mass is hanged by a massless string. By the means of an angle how much does the mass deviate from the Earth's radius due to rotation of the earth? Consider the Earth as a spherical body. Homework Equations Fcp=mv^2/r w=dθ/dt v=wr The Attempt at a...

1. The trajectory of a rock thrown from a height with an initial speed of 20.9 m/s is shown in the figure below. Evaluate the magnitude of the gravitational field at the surface of the planet. The planet has no atmosphere...

Can you give me a link where I can find a simple explanation of the formula of the period of a pendulum? As far as I know, if the angle is 3°, the tension on the rope is g/ cos 3 and the horizontal T = 9,8 * tan 3 (0.0524) = 0.5 N. Is this the only force to consider? Can you tell me how to...

Hello folks! why a formula of type K/r^2 for the gravitationnal interaction is incompatible with the principle of special relativity ? ( the electric field is also defined with the same kind of relations)

I've searched a little bit and found that I can derive kepler's third law from Newton's law of gravitation. That's okay. But I want to deduce kepler's second law too: "An imaginary line joining a planet and the sun sweeps out an equal area of space in equal amounts of time". I know it's possible...

I got a little bit confused while studying gravitational potential energy, particularly the expression for long distances: (-GMm/r). An exercise asks me for the velocity, period and radial acceleration for a 1000kg satellite that I wish to put into orbit. That's okay. But after that, I'm...

Homework Statement 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) Assuming the orbit is circular...

Hi guys! So I am a little congused about Newtonian gravitation. I understand the equation to get a scalar for the strength of gravity, but when I plugged it into a vector field calculator (with random values of m and M), all the vectors only pointed in one way. I do understand that r-hat could...

Homework Statement at what distance above the Earth surface and at what depth below the Earth surface,is the acceleration due to gravity less by 10% of its value at surface? R=6400 km Homework EquationsThe Attempt at a Solution g'/g = (1- 2h)/R

Homework Statement Homework EquationsThe Attempt at a Solution the solution says to equate the moments about C or equate the centripetal forces but the moments, they used M1R1 = M2R2 how does the above represent the moment, and why is the moment even equal?similarly, why is the centripetal...

I have thought about an experiment which to demostrate gravitomagntism: spinning massive cylinder creates gravitomagnetic field above it. Oscillating pendulum above the cylinder departs from its trajectory because of "gravito-Lorents" force. To calculate magnetic force above the cylinder I use...

Homework Statement A piece of an empty rocket booster fuel tank (mass 45 kg) is ejected from a rocket that is 2100 km above the Earth's surface. It is traveling upwards at 4.5km/s at this time. a) what is the total energy of the booster at this time? b) Will it return to earth? Homework...

Homework Statement A spaceship is in a circular orbit of radius ##r_0## about a planet of mass M. A brief but intense firing of its engine in the forward direction decreases the spaceship's speed by 50%. This causes the spaceship to move into an elliptical orbit. a) What is the spaceship's...

It says here that time dilation due to gravity can cause decoherence: http://www.newscientist.com/article/dn27735-Earth's-gravity-may-force-us-to-do-quantum-experiments-in-space.html But.. wouldn't the effect of time dilation be more like a modification of the expected unitary evolution, so...

How did Kepler derive his laws of Planetary Motion without knowing about Newton's law of gravitation? Specifically, the first law of planetary motion which says that planets follow elliptical paths - how did he figure that out without the knowledge of the gravitational pull of the sun? Was it...

Okay so I'm under the understanding that the way gravitation works is that each object warps the space around itself, and essentially objects caught in the warping are "falling" towards the object with the bigger warp in the center. So my question is, how do objects that are complete clones of...

Homework Statement There's a sphere with the mass of the Earth and same radius.It rotates at constant speed. It hhas the period of the earth. a mass of a kg sits on the surface. 1) find grav force on mass 2) find centripetal force on mass 3) find the difference in magnitude between them 4)...

This week (Jun 7-12, 2015) at Penn State: General Relativity and Gravitation: A Centennial Perspective http://event.gravity.psu.edu/index.shtml There will be a live stream of the plenary sessions. For the updated schedule and link to the streams, consult...

Homework Statement Assume that the orbital radius of the Earth decreases from R to R-ΔR due to air drag, provided the change is very small compared to the radius of earth. Then what is change in orbital velocity, change in kinetic energy, change in potential energy and work done by air...

Homework Statement The average orbital radii about the Sun of the Earth and Mars are 1.5*11^11 m and 2.3*11^11 m respectively. How many (Earth) years does it take Mars to complete its orbit? Answer: 1.9 years. Homework Equations F = G * ((m1*m2) / r^2) F = m*(w^2)*r T^2 = (4Pi^2 / G*m)*r^3; m...

Homework Statement A planet of radius R = (radius of earth)/10 has the same mass density as earth. Scientists dig a well of depth R/5 on it and lower a wire of the same length and of linear mass density 10-3 kgm-1 into it. If the wire is not touching anywhere , the force applied at the top of...

Homework Statement A body is suspended on a spring balance in a ship sailing along the equator with a speed ## v' ## . If ## \omega ## is the angular speed of the Earth and ## \omega_0 ## is the scale reading when the ship is at rest , the scale reading when the ship is sailing, will be very...

Homework Statement While solving a question on gravitation I had to consider a very thin spherical layer of a uniformly dense sphere. It's written in the solution that : "Then the considered layer is attracted to the part of the sphere lying within it (outer part doesn't act on the layer)...

This is the link to the relevant paper. I have to show that vector (t', x', y', z') lies on the sphere. But for that to be, V^2 has to be 1 according to the equation in the introductory part of the section 2. That, by definition, means that E=-m/2. What does that mean, and why is this solution...

Homework Statement The question says that : A planet of mass ##m## moves along an ellipse around the sun so that its maximum and minimum distances from the sun are equal to ##r_1## and ##r_2## respectively. Find the angular momentum ##M## of this planet relative to the centre of the sun...

Homework Statement As a moon follows it's orbit around a planet, the maximum gravitational force exerted on the moon by the planet exceeds the minimum gravitational force by 11%. Find the ratio rmax / rmin, where rmax is the moon's maximum distance from the center of the planet and rmin is...

1. The problem statement, all variables and given/known according to my calculus III textbook, the gravitational force acting on an object at ##x = <x,y,z>## is ##F(x)=-\frac{mMG}{|x|^3} x ##. What's the point of having a cube on the bottom. Why shouldn't I memorize it as...

Homework Statement Jupiter has a core of liquid metallic hydrogen, with uniform density $\rho_c$, with radius $R_c$. This is surrounded by a gaseous cloud $R_g$, where $R_g>R_c$. Assume the cloud is of uniform density $\rho_g$. The problem also specifies that we are to assume both regions of...

Homework Statement Suppose we had a straight tunnel, through Earth's center, to a point on the opposite side of the planet, and used it to deliver mail to the other side. With what speed would our packages pass through Earth's center. Homework Equations ag = (GM)/R2 Mins = (4/3)πR3*ρ The...