Gravitation Definition and 918 Threads

I was reading a book and it said that: Can someone please explain me what did Newton mean by " we can send signals at infinite speed, and I don't find any relation between the instantaneous nature of G.Forces and "sending signals at infinite speed"... So what did Newton exactly mean?

Some time ago I began my research in gravitation. Now I am actively working in GR and quantum gravity. I am sorry to say this but when I more study it, more I think that GR is not correct after all. For some criticism to GR, you can see the last part of my "paper" on string theory sited in...

Okay, I've looked over all of my formulas numerous times and I just can't figure out what to do for these two: In terms of Earth radii, how far from the center of the Earth would you have to travel in order to cut your weight from 900N to 300N? The gravitational force between two...

Gravitation doubt... This is supposedly a simple conceptual problem but I still have a doubt about this: A satellite is orbitting the Earth with a constant speed when suddenly the force of gravitation disappears(no explanation as to how that happened!). Then the satellite will: a)...

Here is a paper of special interest to me. The authors model inertia and gravitation as effects of the EM fields. http://xxx.lanl.gov/PS_cache/gr-qc/pdf/0504/0504061.pdf Unfortunately, they still model the ZPE fields as if they were pretty flat. This is not logical, because if the ZPE...

Can anyone give me a clear and good explanation of Newtons Law of Gravitation, Keplers Law & Orbital Motion.

How would i go about doing a problem like this? A 1500 kg satellite is orbiting the Earth at a height of 250 km. How much work would it take to move it into an 800 km orbit?

Here is my problem: The star is 59 light years from the Earth and has a mass of 1.90×1030 kg. A. A large planet of mass 1.20×1028 kg is known to orbit this star. The planet is attracted to the star by a force of 3.50×1026 N when their centers are separated by a distance equal to the...

We all know that moon is under the influence of Earth gravitational force and vice versa. This force causes the circular motion of Moon (and Earth as well). Earth pulls Moon with a force F and Moon pulls Earth with the same force. This has occupied me a long time: Will Moon eventually fall down...

A 1500 kg satellite is orbiting planet earth. The period is 86400 seconds and the radius is 42200000 meters. To determine the magnitude of attractive force... you use equation F=GM(sat)M(Earth)/R2. I know that the mass of Earth is 6.0*10(exp)7 kg and the gravitational constant is 6.67*10(exp...

You have one screwdriver with a thick handle and one with a thin handle. Which one would be better for opening a stubborn can of paint? my answer: either screwdriver--they are the same Which screwdriver would be better for turning a stubborn screw? my answer: the thick handled screw...

How much energy is required to move a 1070 kg object from the Earth's surface to an altitude four times the Earth's radius? Having problems with this question. I figure it would be GMm(1/r(final) - 1/r(initial)), with the final being 4x Earth's radius, and initial being Earth's radius. I...

If I have an infinite slab of incompressible self-gravitating fluid of density rho within the region |z|<a, and I am asked to find the potential both inside and outside the slab, where should I start?

Calculate the ratio of the energy that would be required to put a mass M into orbit near the Earth's surface (if there were no friction) and the energy to put the same into distant space. I'm stuck. How am i suppose to calculate the ratio. I know the that the energy to put M into orbit near...

Which is larger - the total energy of the 2.00 kg satellite in its 160. km orbit or the total energy in its 144 km orbit. Explain why the two answers are different. Ok the total energy of 2.00 satellite in 160km orbit is -6.09x10^7 J and the total energy of 2.00 satellite in 144km orbit is...

As far as I read, gravitation or better: gravitational waves expand with c. However, particles like photons which are moving along with c are subject to the curvature of space. Regarding a black hole, light cannot escape with c but gravitation can. Is gravitation thus faster than c? Carsten

Has anyone read Gravitation from the Ground Up, B.F. Schutz? What did you think of it? Pete

The Explorer VIII satellite, placed into orbit November 3, 1960, to investigate the ionosphere, had the following orbit parameters: perigee, 459 km; apogee, 2289 km (both distances above the Earth's surface); period, 112.7 min. Find the ratio vp/va of the speed at perigee to that at apogee.

The Explorer VIII satellite, placed into orbit November 3, 1960, to investigate the ionosphere, had the following orbit parameters: perigee, 459 km; apogee, 2289 km (both distances above the Earth's surface); period, 112.7 min. Find the ratio vp/va of the speed at perigee to that at apogee.

hi! title tells all

A uniform solid sphere with radius R produces a gravitational acceleration a(g) on its surface. At what two distances from the center of the sphere is the gravitational acceleration a(g)/3? I know that gravitational acceleration = GM/r^2, and that on the surface of the sphere, a(g) = (4 pi G...

In Figure 13-34, a square of edge length 21.0 cm is formed by four spheres of masses m1 = 6.00 g, m2 = 3.00 g, m3 = 1.00 g, and m4 = 6.00 g. In unit-vector notation, what is the net gravitational force from them on a central sphere with mass m5 = 2.40 g? Well by using Newton's Law of...

Hi everybody, Does someone know if mass shrinks while it emits gravitation? What I mean is either the gravitation field point of view: Does mass need to continuously produce a field of gravitational force and by this lose energy? Or the particle view: If mass continuously emits...

I was wondering if any of you could explain how Newton derived his Law of Gravitation: F=G*m_1*m_2/r^2 ? If this question is to vague tell me, thanks guys.

1. How can i prove that Eg = mgh 2. What is the total energy needed to place a 2.0x10^3-kg satellite into circular Earth orbit at an altitude of 5.0x10^2 km? For number 2, the answer is apparently 6.7x10^10J. However, shouldn't Total Energy = 1/2 (Eg)? If that is the case, the...

Hello, I'm having trouble with the following question: There is a spherical hollow inside a lead sphere of radius R ; 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 . With what...

As you get further away from the Earth's surface your gravitational potential energy increases, but when you get closer center of the universe (or something like that) your gravitational potential is decreasing... ? Meaning when you are the FURTHEST away from the Earth's surface your...

anyone know how to do this problem?? [COLOR=Navy]Tom has a mass of 65.7 kg and Sally has a mass of 52.9 kg. Tom and Sally are standing 28.7 m apart on a massless dance foor. Sally looks up and she sees Tom. She feels an attraction. If the attraction is gravitation, find its magnitude. Assume...

I can not figure out what is wrong with this : suppose one deals with a multiple connected universe, such as a torus. In order to make it simple, let us imagine we consider two very massive objects in this topology, say two well separated clusters of galaxies whose distances are large compared...

Can two objects move towards each other as a consequence of their gravity a distance smaller than one Planck unit of length?

This is my first post here, so I will introduce myself. I'm Allen, just a 16 year old interested in physics and eager to learn more. So I was reading Brian Greene's The Elegant Universe and a few ideas and examples involving gravity dawned on me. I am sure that they have been addressed...

Hello I am having a lot of difficulty figuring out these last four problems for my homework. if anyone can help me I would greatly appreciate it. My teacher is refusing to help me for some reason. THanks! 1.planet Jupiter is about 320 times as massive as the Earth. Thus, it has been claimed...

If you have two particles that are even billions of light years away from each other, is there any gravitational pull between then? (Considering the possibility that there is nothing else in the universe)

hi, here's the problem I'm working on. a spacecraft is passing by an asteroid. the spaceship is moving at 10 m/s relative to the asteroid. here is picture X (spaceship) -=> 10 m/s | |...

When a large star goes supernova, it will become a black hole. Is the gravitational field of the black hole larger than that of the original star? At least at a distance, not close to the singularity. It seems to me that the mass of the black hole is smaller than that of the star, because a lot...

I'm stuck on the following question: Newton's law of universal gravitation is represented by the following equation. F = GMm/r2 Here F is the magnitude of the gravitational force exerted by one small object on another, M and m are the masses of the objects, and r is a distance. Force has...

What are the flaws with this theory? http://www.gravitywarpdrive.com/NGFT_Chapter_8.htm :eek: :eek: :eek:

I just have a question about relationships between physical quantities. Is it true that if: z \propto x \ \textrm{and}\ \ z \propto y then z will always be in the form: z = Cxy Where C is a constant? What prompted me to ask was Newton's Universal Law of Gravitation. In...

Hi, me again. I have another question concerning the gravitation equation. My physics book shows through a proof that the escape velocity of an Earth satelite is just sqrt(2) greated than the orbital velocity. But I am having trouble seeing how this is so. My instinct tells me that if I increase...

Thanks for you help on the first post. I just have two follow up questions. So I understand now that the moons acceleration is part of its circular orbit, but what about the acceleration of the earth. How can I picture that? If I consider the Earth stationary, then the moon orbits the earth, and...

Hi, I've been reading on the laws of gravitation, let me just say, WOW, how can a man like Newton think of something that obscure. SHEESH! Anyways, I can see how each body gravitates with an equal and opposite force towards each other. Now, if this is the case, how come the moon and the Earth...

we all learn this law. It state that the force between two bodies of mass m_1 and m_2 is attractive in nature. The gravitational attraction F is directly proportional to the product of the masses of the two bodies and inversely proportional to the square of the distance between them. From the...

Light leaves the Sun, it takes *8 minutes to reach earth, how long does a Gravitational Signal take to get from the Sun to Earth? Does Space have a Velocity?..what is the derived speed of Gravity through a near Vacuum, one that has no Matter , actually does gravity signals become null?

Hello all! I bet this is incorrect forum to post the question like this, but i hope moderators won't punish me too much for this :redface: i wonder, does anybody of you have a printable version (with good quality!) of Gravitaion (von Charles W. Misner, Kip S. thorne, John Archibald Wheeler) in...

You all know the equation. F=G x M x m div by d squared. I would like to know what Newton's gravitation constant represents. I would appreciate it if someone could tell me the procedure. By what measurments are the two masses weighed (kilograms, etc.)? Do you first multiply the two masses...

The first one just confuses me because of the word in the brackets. 1. A 70kg boy stands 1.0 m away from a 60 kg girl. Find the force of attraction (gravitational) between them. For this would I just sub the values into F=Gm1m2/r^2? The second question is giving me a lot of problems...

whats up guys. help me out NASA is giving serious consideration to the concept of solar sailing. A solar sailcraft uses a large, low-mass sail and the energy and momentum of sunlight for propulsion. The total power output of the sun is . How large a sail necessary to propel a 10,000-kg...

I am not very well versed in quantum mechanics, however I was reading a theory stating that the strong and weak nuclear forces are the same. Any opinions? By combining and analyzing the principles of Electrostatics, Isaac Newton’s Law of Gravity, Quantum Mechanics, and Einstein’s...

Gravitation Problem (stuck on Algebra!) We just started Gravitation in my Physics class. Here is the problem: How far from Earth must a space probe be along a line toward the Sun so that the Sun's gravitational pull on the probe balances Earth's pull? Sorry I'm really bad with the...

A "concept" question... I think the answer is yes... which means it probably is a definite "no." The sun is directly below us at midnight, in line with the Earth's center. Are we then heavier at midnight, due to the sun's gravitational force on us, than we are at noon? Explain.