Gravitation Definition and 918 Threads

Homework Statement The Andromeda galaxy is at a distance of 2.1 X 1022 m from our Galaxy. The mass of Andromeda is 6 X 1041 kg and the mass of our Galaxy is 4 X 1041 kg. (a) Gravity accelerates the galaxies toward each other. As reckoned in an inertial reference frame, what is the...

Homework Statement Some people believe that the Moon controls their activities. The Moon moves from being directly on the opposite side of Earth from you to be being directly overhead. Assume that the Earth-Moon (center-to-center) distance is 3.82 multiplied by 108 m and Earth's radius is 6.37...

Greetings, I've been pondering something and hope someone here can help me understand this. Simply put, have any experiments confirmed that individual atoms and/or free particles like neutrons, protons, electrons, anti-particles, etc are affected by gravity when they are not constituents of...

Hello! I'm stuck on these two problems, any help is appreciated! 6.5 Homework Statement Use radar as a distance-measuring device. The radar set measures its proper time \tau between the instant at which it emits a pulse and the later instant when it receives the reflected pulse. It then...

What are the problems in Newton's law of universal gravitation? Please explain using simple physics if possible.

Homework Statement A. The mass ratio of the Earth and the moon is 81:1 and the earth-moon separation is 3.8x108m. At which position between the Earth and the moon is the gravitational potential at a maximum? B. Which of the following statement about a communication satellite in parking...

Homework Statement Please give an example when the following condition is true- Gravitational Potential is zero and gravitational field intensity is non-zero. Homework Equations The Attempt at a Solution

Homework Statement 1.A satellites are placed in a circular orbit that is 1.43 × 10^8 m above the surface of the earth. What is the magnitude of the acceleration due to gravity at this distance Homework Equations 1.I used G*mE/r^2 The Attempt at a Solution 1. Got an answer of .0195m/s^2 I...

I'm trying to understand the basics of gravity. Newtons law of universal gravitation gives us : F1 = F2 = G (m1m2)/r2 Now on Earth you can simply that down to F = mg where g = G (mearth/R2) But using f = mg, a heavier object say a tennis ball should fall faster than a cannon ball. But...

Homework Statement Which of the following statements about Newton’s Universal Law of Gravity is false? A. The heavier mass exerts a force on the lighter mass that is equal but opposite to the force the lighter mass exerts on the heavier mass. B. A heavy mass from far away can exert the...

I'm working on a problem on relating gravitation and simple harmonic motion. The idea is that a mass dropped in a hole drilled through the Earth will oscillate (no friction, etc). The question asks this: "Show that the motion of the mass is simple harmonic motion and find a formula for r(t)"...

hello, I'm not saying that Newton's law of universal gravitation is really wrong but there are phenomenons which i don't think the law is really correct and i want someone to help me. There might be explanations but i don't really know any explanations right now so an explanation would be...

Homework Statement At what distance from teh Earth will a spacecraft on the way to the Moon esperience zero net force due to these two bodies because the EArth and Mon pull with equal and opposite forces? Homework Equations net force = m a a radial = r^-1 v^2 Fg = r^-2 G M m...

I don't understand the physical meaning of one of my dimensions/variables. Let there be a gravitational potential \phi (x_a), a=1,2,3. Equation of motions of a freely falling particle is: \frac{d^2 x_a}{d t} = - \frac{\partial \phi}{\partial x_a}. If there are 2 particles falling, family of...

Hi there, I don't understand why the equal of Newton's law of gravitation F = Gm1m2/d(squared) is different for no spherical objects. In the image of my attachment there are one spherical object and a no spherical object. So why if there are not very distant the equal used is F =...

Is there a name for the DE given by Newton's law of gravity: f''(x) f(x)^2 = -1 ?

Hi all, Does Newton's law of universal gravitation depend on the geometry of the manifold? For example, what happens to formulas if we take the projective plane as our universe? How can one model "the mass" on the projective plane or on torus? I am a math grad with very elementary...

What does strength mean exactly in this context below. Is this the acceleration imposed by M on m? Strength of gravitational field created by a mass M: g = F/m = -G(M/r^2)r^unit

In the Einstein's theory of general relativity, the gravitation is an attribute of curved spacetime instead of being due to a force propagated between bodies. But the quest for the famous graviton does not presume that gravitation is due to a force? Is the quantum gravity conflicting with the...

Homework Statement The three spheres in Fig. 13-45, with masses ma=80g ,mb=10g and mc=20g, have their centers on a common line, with L=12 cm and d=4cm. You move sphere B along the line until its center-to-center separation from C is d=4cm. How much work is done on sphere B (a) by you and (b)...

Hi, I have attempted a basic gravitation question from “Classical Mechanics” R. Douglas Gregory (1st ed). I get the answer provided at the back of the book, but it doesn't make sense to me. Can someone help me interpret the answer? Question: Pg 71, Q3.3 A uniform rod of mass M and...

Homework Statement In Fig. 13-41, a particle of mass m1 = 0.23 kg is a distance d = 84 cm from one end of a uniform rod with length L = 6.4 m and mass M = 2.4 kg. What is the magnitude of the gravitational force on the particle from the rod?Homework Equations...

Homework Statement Figure 13-39 shows a spherical hollow inside a lead sphere of radius R = 4.5 m; the surface of the hollow passes through the center of the sphere and “touches” the right side of the sphere. The mass of the sphere before hollowing was M = 380 kg. With what gravitational...

I am trying to learn more about General Relativiity. We had Newton's Law of Gravitation. When does it not work? I heard at very high speeds, high mass bodies, and when the distance to a high mass body is very short (Mercury for example, I think)? How does Newton's Gravitation differ...

I'm trying to figure out these two problems and I'm so lost! 1. Two planets are circling a star. The second planet has an orbit 4 times the size of the first planet. By the time the first planet revolves once, how many times the second one will? My solution: the formula is T=2PiR/v... so...

Hi all! It is often said that Newton deduced from Kepler's laws the theory of gravitation. Particularly from (T^2)/(a^3)=const for differnet planets he deduced that gravitational force must look like '1/(r^2)'. I can also do that by writing F=ma and integrating it in spherical coordinates, but...

Recently I read that gravitation and electromagnetism is unified by Kaluza-Klein theory. Can someone tell me in depth how they are unified

Homework Statement A 450kg satellite is to be placed at an altitude of 2.45 x 10^6m above the Earth surface. Calculate the period the satellite will have when orbiting at that altitude. Homework Equations m2g = Gm1m2/R^2 = m2v^2 = m2(4pie)^2 R /T^2 = m2 2pie v/T Ac=4pie ^2 R / T^2...

why can't we see it as dimension like time?

Here is the succinct story of apple which fell on Sir Newton. Since both apple and Earth attract each other with a force equal in magnitude from both sides but apple move faster towards Earth because of its greater acceleration than negligible acceleration of earth. So Newton derived the...

Combining quantum mechanics with general relativity supposedly yields infinite gravitation, between the gravitons if I have understood this correctly (correct me if I'm wrong). String theory supposedly does away with this infinite gravitation -- my question is, how does it do this...

Homework Statement Comets travel around the sun in elliptical orbits with large eccentricities. Suppose the comet has an initial speed of 1.17*10^4 m/s when at a distance of 4.9*10^11 m from the center of the sun, what is its speed when at a distance of 5.9*10^10 m? Give your in m/s in...

Homework Statement A rocket accelerates to speed v0 near the Earth's surface,and then coasts upwards. Show that if v0 = 2sqrt(gR) where R is the Earth's radius, then very far from the Earth the rockets speed will be v = sqrt(2gR) Homework Equations The only equations I have thought...

Homework Statement A 11 kg satellite has a circular orbit with a period of 1.0 h and a radius of 4.9 × 10^6 m around a planet of unknown mass. If the magnitude of the gravitational acceleration on the surface of the planet is 41 m/s^2, what is the radius of the planet? The attempt at a...

So, I'm going over this bit in the beginning of MTW's Gravitation where they give an equation for changing acceleration from time coordinate t to time coordinate T(t): \frac{{d}^{2}x}{{dt}^{2}} = \frac{d}{dt}(\frac{dx}{dT}\frac{dT}{dt}) = \frac{{d}^{2}T}{{dt}^{2}}\frac{dx}{dT} +...

Homework Statement How far from the surface will a particle go if it leaves the asteroid's surface with a radial speed of 1000 m/s? The radius of the asteroid is 565000 m, and the gravitational acceleration near the surface is 2.7 m/s^2 Homework Equations The Attempt at a...

Homework Statement If a uniform sphere of mass M and radius R, is height h above an infinite sheet of uniform density \rho_{s}, what is the gravitational force of the sphere, on the sheet. Homework Equations F=\frac{GMm}{R^{2}}; \Phi=\frac{GM}{R}; \nabla\bulletg=4\piG\rho; U=m\Phi...

Homework Statement Starting with Newton's law of gravitation, determine the height h one person has to go from the surface of Earth in order for the person's weight to be reduced to 1/5 of their weight at the surface of the Earth. The only information you are given is that the radius of the...

The other day I was reading a simple experiment to determine (yes, very roughly) the constant of gravitation, all using simple tools in your basement. http://www.fourmilab.ch/gravitation/foobar/" What struck me about this experiment is another that I remember from childhood cartoon...

I was reading this very small section in my physics book and can't seem to come to grips with its concept. It starts off with Newtons shell therem being applied to a particle located inside a uniform shell and that the shell exerts no 'net' gravitational force on a particle inside it. It...

Homework Statement A square of edge length 19.0 cm is formed by four spheres of masses m1 = 5.10 g, m2 = 3.00 g, m3 = 1.20 g, and m4 = 5.10 g. In unit-vector notation, what is the net gravitational force from them on a central sphere with mass m5 = 3.00 g? Homework Equations...

If the distance between two objects is zero, won't there be infinite gravitational attraction force between them? How would the objects can get separated?

classically, acceleration towards the Earth's surface is described by a=G*m/r^2 usually we think of using this formula to calculate the force of gravity as we rise away from the Earth's surface. but consider what would happen if if you traveled through a tunnel to the center of the earth...

Homework Statement Each mass is 4kg find the magnitude and direction of the net gravtitational force on mass A due to the other masses. each side of the square is 10cm http://img13.imageshack.us/img13/3815/1012447.jpg I am having trouble with (b) the square Homework Equations F =...

Hi everyone. I know about the equations of gravitation but something is still bothering me. The equation for total energy of a satellite in an orbit is -GMm/2r However, when the satellite suddenly lose control and heads to the Earth, why does the total energy in the system change according...

Homework Statement In an old-fashioned amusement park ride, passengers stand inside a 5.4-m-diameter hollow steel cylinder with their backs against the wall. The cylinder begins to rotate about a vertical axis. Then the floor on which the passengers are standing suddenly drops away! If all...

I have searche many general relativity texts and have not found an answer to the following question: How does curvature translate into the Newtonian idea of gravitation? For example, how is Newton's law of gravitation, where all matter attracts all matter, an approximation to the idea of...

Homework Statement Mars travels around the Sun in 1.88 (Earth) years, in an approximately circular orbit with a radius of 2.28 x 10^8 km Determine a) the orbital speed of Mars (relative to the Sun) b) the mass of the Sun Homework Equations acceleration centripetal = 4(pi^2)(r) /...

Homework Statement The mass of the Moon is 7.36 x 10 ^ 22 kg. At some point between Earth and the Moon, the force of Earth's gravitational attraction on an object is canceled by the Moon's force of gravitational attraction. If the distance between Earth and the Moon (center to center) is 3.84...

I've had this on my mind for a while. I'm pretty confident that I have the right idea, but I can't find a formula that I could use to prove it to someone. So, here it is. Imagine a sphere of space-time with absolutely nothing inside of it. It is a large sphere, sun-size large. Now, take...