Gravitation Definition and 918 Threads

Suppose an object is dropped from height h, where h < R but gravity is not constant). Show that the speed with which it hits the ground, neglecting friction, is approximately given by: v = sqrt(2gh)(1 - (h/2r)) where g is the acceleration due to gravity on the surface of the Earth. HINT...

Do higher energy photons have the same trajectory around planet/gravity as low energy photons? I.e: If you were shooting photons from the same position wrt a planet would their path be the same?

Homework Statement Given if: (1) Fsm + Fem = Mm x Ams (2) Ams = Ame + Aes (3) Res ~= Rms Show that (4) Fem ~= Mm x Ame Where: 'Fsm' is the force between the sun and moon, 'Fem' the force between Earth and moon, etc. 'Mm' is the mass of the moon, 'Ams' the accelleration of the...

(Offtopic from another thread) So I have a super-duper laser which can emit a very short but extremely powerful pulse in some direction. This pulse is so powerful that the energy of light is say 1Kg * c**2, or the relativistic mass of light is 1Kg. What is a gravity from that light...

Homework Statement Two satellites are launched at a distance R from a planet of negligible radius. (Yes, that's what the problem says...) Both satellites are launched in the tangential direction. the first satellite launches correctly at a speed v_0 and enters a circular orbit. The second...

Homework Statement The planet Uranus has a mass about 14 times the Earth's mass, and its radius is equal to about 3.7 Earth radii. A)By setting up ratios with the corresponding Earth values, find the free-fall acceleration at the cloud tops of Uranus. B)Ignoring the rotation of the planet...

Homework Statement Two objects attract each other with a gravitational force of magnitude of 1*10^-8 N when separated by 20 cm. if the total mass of the two objects is 5kg, what is the mass of each. Homework Equations Fg=G*m1*m2/r^2 The Attempt at a Solution i know everything that...

1. If the INternational space station has an orbital velocity of 9,000 m/s. find the time (in minutes) it takes to make one complete orbit. Relevant equations F = mv2/ R = m4[pi]2R / T2 The attempt at a solution Is this the way to solve for T? Do I use Earth mass and Earth R b/c that...

Homework Statement Distance of Earth from Sun = 1.50 x 10^11m Period = 365.2 days Distance of Mars from Sun = 2.28 x 10^11km Period of Mars in Earth Years? Homework Equations (Ta/Tb)^2 = (Ra/Rb)^3 The Attempt at a Solution (365.2 days/Tm)^2 =(1.50 x 10^11m/2.28x10^14m)^3...

Ok I got most of them but am having trouble on a few of them. The question is: The Sojourner rover vehicle shown in the sketch above was used to explore the surface of Mars as part of the Pathfinder mission in 1997. Use the data in the tables below to answer the questons that follow. Mars...

gravitation constant has been determined experimentally by cavendish. Its value has been found to be always a constant. The expression for G is given as G=Fd*d/Mm. I would like to know- on what factors does gravitation constant depend?

Einstein's "The Field Equations of Gravitation" Paper I'm trying to find a translated copy of this paper - but i can't find one anywhere! The 1905 papers are all over the place; i thought the this would be similar. Does anyone have a copy, or recommendations on where to look? Thanks...

a black hole is an object so heavy that neither matter nor even light can secape the influence of its gravitational field. Since no light can scape from it, it appears black. Suppose a mass apporxmiately the size of the Earth's mass 5.56x10^24 kg is packed into a small unifrom sphere of radius...

Homework Statement Some people say that the tides on Earth are caused by the pull of the moon. Let us investigate whether this is true. (a) Determine the forces that the moon and the sun exert on a mass, m, of water on Earth. Your answer will be in terms of m with units of N. (c)...

Homework Statement Three(3) 10kg spheres form a triangle with the first sphere being at the top, the second sphere being at the bottom right cornern and the third sphere being at the bottom left corner. All sides of the triangle are 1.0m. Calculate the net gravitational force on the 3rd...

Homework Statement Traffic is expected to move around a curve of radius 200m at 90km/h. What should be the value of the banking angle if no dependence is to be placed on friction? Homework Equations ΣFc = mac The Attempt at a Solution For this question what I did first was draw a...

Can gauss law in its equivalent form be used to determine the gravitational field?? If so how??

1. Homework Statement Two "swarms" of krill each contain 1.200×107 identical individuals. The centers of gravity of the "swarms" are 15.0 meters apart. By what factor will the gravitational force of attraction between the two "swarms" change, if 9.231×106 new krill join each "swarm?" Use...

I am not looking so much for answers to problems, but I was sick the day of this lecture and need some clarification. I think I understand what to do, but some support would be great. Homework Statement What is the gravitational force acting on a sphere on particle 'm' located at distance 'r'...

Homework Statement What minimum energy is required to raise a 1.7e3 kg vehicle from the surface of the moon to a height of 5.22e6 m? Homework Equations Ep= -G(m1m2)/r The Attempt at a Solution Ep(initial)= -6.67e^-11(1.7e^3 x 7.35e^22)/1.74e^6 = -4789750000 Ep(final)=...

Homework Statement (1) A uniform wire with mass M and length L is bent into a semicircle. Find the magnitude of the gravitational force this wire exerts on a point with mass m placed at the center of curvature of the semicircle. (2) Mass M is distributed uniformly along a line of length...

Homework Statement Assuming that we know the density of Earth as a function of radius, we have to derive the equation for gravity as the function of radius. Homework Equations The Attempt at a Solution lets us choose density as \rho(r). I know that within a hollow sphere there is no gravity...

There is a Magnetic and Electric Field around every planet and the sun due to the dipole action they produce. They vary with a factor of r^-3. Are these forces the stuff that gives gravitational forces its name or is there more to it?

Homework Statement Mars Data: Radius = .53 * Earth's Radius Mass = .11 * Earth's Mass Find the acceleration due to gravity on Mars in terms of g, the acceleration due to gravity on Earth. Homework Equations g=Gm / r2 The Attempt at a Solution gm= G(.11 ME) / .53rE2 gE =...

If the gravitation has very very tiny deviation from inverse square law！our solar system became unstable? If so ,how long people on the Earth can notice it? Thank you in advance!

If the gravitation has very very tiny deviation from inverse square law！our solar system became unstable? If so ,how long people on the Earth can notice it?

Homework Statement Our sun rotates about the cneter of the galaxy (m = 4*10^41kg) at a distance of about 3*10^4 light years ( 1ly=(3*10^8m/s)*(3.16*10^7 s/y) what is the period of our orbital motion about the center of the galaxy? Homework Equations Okay so I believe you would use...

http://fisica.ufmt.br/school2/ Some of the invited speakers: Paul Davies, Abhay Ashtekar, Lawrence M. Krauss, James B. Hartle (to be confirmed), etc.

Homework Statement http://i241.photobucket.com/albums/ff4/alg5045/1012540B.jpg Consider the Earth following its nearly circular orbit (dashed curve) about the sun. The Earth has mass 5.98 *10^24 kg and the sun has mass 1.99 *10^30 kg. They are separated, center to center, by r=93 million...

If a 10 solar mass star explodes, leaving behind a 5 solar mass black hole, and blowing off an idealized spherical symmetrical (5 solar mass) neutrino shell, would the gravitational field (i.e. curvature of manifold) change? http://en.wikipedia.org/wiki/Supernova p.s. addendum: could Newton...

Homework Statement The Stardust spacecraft was designed to visit a comet and bring samples of its material back to the earth. The craft is 1.7 m across and has a mass of 385 kg. In January 2004, from a distance of 237 km, it took the photograph of the nucleus of comet Wild2, shown in the...

Homework Statement For a spacecraft going from the Earth toward the Sun, at what distance from the Earth will the gravitational forces due to the Sun and the Earth cancel? Earth's mass: Me the Sun's mass: Ms Earth-Sun distance: r Homework Equations F=Gm1m2/r^2 The Attempt...

At what center-to-center distance from the Earth would a 0.9 kg mass weigh 0.9 N? I used equation g = GM/r^2 to get an answer of 8.17 X 10^-6 which is incorrect. Am I using the correct formula? Thanks

Homework Statement A satellite of mass m, initially at rest on the earth, is launched into a circular orbit at a height equal to radius of the earth. What is the the minimum energy required for this purpose? Homework Equations GMm/r^2 = mv^2/r PE at surface = -GMm/R PE at orbit =...

The moon Europa, of the planet Jupiter, has an orbital period of 3.55 days and an average distance from the centre of the planet equal to 671,000 Km. If the magnitude of the gravitational acceleration at the surface of Jupiter is 2.36 times greater than that on the surface of the Earth, what is...

I'm having a problem with a project I've been kicking around for some time now. This arose out of a discussion with a co-worker who was wondering how much less one would weigh at various intervals of increasing altitude above the surface of the earth. I set out to create a spread sheet to...

Homework Statement a). Four particles, each of mass m , are situated at the vertices of a regular tetrahedron of side a. Find the Gravational force exerted on anyone of the particles by the other three b) Three uniform rigid spheres of mass M and radius a are placed on a horizontal table and...

Homework Statement A body is fired vertically from the ground of the Earth with a velocity v_0=1km/s. If the gravitational force is not considered as constant and supposing that the Earth is a sphere of radius 6371km, a)Find the maximum height reached by the body. b)Compare the previous...

Homework Statement Suppose that the Earth is a sphere with a radius of 6371 \text{ km} and that its uniform density is worth 5517 \text{ kg}/m^3. Suppose also that the acceleration of the gravity on its surface is g=9.80665 m/s^2. Calculate the value of the universal gravitation constant...

Homework Statement Four particles, each of mass m , are situated at the vertices of a regular tetrahedron of the side a. Find the gravitational force exerted on anyone of the particles by the other three. Homework Equations F=m*M*G/R^2 The Attempt at a Solution Since the mass...

I am having some problem understanding this.. By Newtons Gravitation Law we know: F=Gm1m2/r^2 centre of the particle means r=0, am I right? if so, the equation says that the force will be infinite on the centre of the earth.. but we see that it has 0 force on the centre.. why such thing...

hello, I was wondering if there is an equivalent gauss' law for gravitation like: \Phi=4\piG*Menclosed any help would be appreciated. Thank you.

Homework Statement Show that, at the bottom of a vertical mine shaft dug to depth D, the measured value of g will be g = g_{s}\left(1-\frac{D}{R}\right)g_{s} being the surface value. Assume that the Earth is a uniform sphere of radius R. Homework Equations F = \frac{GMm}{r^{2}} V_{S} =...

Homework Statement planet with mass m and uniform density and radius r, show by integration that the force this body generates on say a satelite is equivalent to a point mass m at the center of the planet Homework Equations i know that gravitational pull is inversley to r*r The...

1. "http://en.wikipedia.org/wiki/Gravitation" " is a general term describing the attractive influence that all objects with mass exert on each other. 2. The http://en.wikipedia.org/wiki/Photon" is massless,has no electric charge and does not decay spontaneously in empty space. My question...

Newton's law of universal gravitation is only valid for point masses. Is it just chance that a person on the Earth experiences the same force of gravity that he would if he were on a shell of no mass and the same radius of Earth with a single point at the shell's center which had the mass of the...

A satellite is in a particular orbit. Too put it in a higher orbit(greater distance from earth), we increase its velocity. I suppose this statement is correct. But when we fire an object from earth, its velocity is lesser for greater distances from earth. Can anyone please simplify this...

Begin with two stars in space, A is 1 solar mass in size, B is two solar masses. The distance between them is such that the equation for gravitational attraction works out to 3 meters per second squared. It seems to me that with A being smaller, it will accelerate towards B at the rate of 2...

[SOLVED] Quick question on universal gravitation - I think I'm right - need clarifica Homework Statement What would happen to the weight of an object if its mass was doubled while its distance from the center of the Earth was also doubled? a) The weight would double. b) The weight would...

Welcome I would like to ask about one thing which always attracts my curiosity. I wonder if anybody can explain the mathematics hidden in gravitational force law for instance. Why there is a force inversely proportional to the square distance? The mysterious thing in it is that there is a...