Gravitation Definition and 918 Threads

Homework Statement Prove the equation: T = 2 pi * sqrt(L/g), then determine the period of a "seconds pendulum" (period = 2 sec on Earth) on the surface of the moon. Homework Equations T = 2pi * r/v T = 2pi/ω ar = rω2 The Attempt at a Solution Do you assume ar is ag? T = 2pi/ω = 2 * pi...

According to the concept: when a planet revolves around a star, and when both the bodies move in circular orbits due to the interaction between each other, both the bodies can be replaced by a single body of mass ##\mu## revolving in a circular orbit of radius equal to the distance between both...

Homework Statement The Earth has a mass of 5.98 x 1024 kg and the moon has a mass of 7.35 x 1024 kg. The distance from the centre of the Moon to the centre of the Earth is 3.84 x 108 m. A rocket with a total mass of 1200 kg is 3.0 x 108 m from the centre of the Earth and directly in between the...

Homework Statement PART 1: Objects with masses of 125 kg and 548 kg are separated by 0.385 m. A 63.5 kg mass is placed midway between them. Find the magnitude of the net gravitational force exerted by the two larger masses on the 63.5 kg mass. The value of the universal gravitational constant...

What would be the easiest way to describe the similarities and differences between the two laws, other than the fact that their formulas are built similarly and they use different measurements. Any input would be great; I am currently having a brain block! Coulombs Law:F=K (q1*q2)/r^2 Newtons...

If Einstein proved that light (a massless object) can be bent because of space-time. Then what happens to Newton's gravitation equation F = Gmm/r^2. Obviously this cannot apply to light, so technically this should fall completely, having both Newton's and Einsteins discovery working at the same...

Bodies in orbit around the Earth are, as I understand it, weightless. Suppose, then, that by some unimaginable process the Earth expanded to a radius equivalent to the orbital radius of a geostationary satellite, but retained the same mass. Does that imply that a body lying on the equator of the...

Hi, According to Newton, F= (GM¹M₂)/r² Einstein proved that light bends around massive bodies, due to gravity. (because space bends around these bodies) Mass of light = zero, but its being affected by gravity. So, is Newton's equation not universal?

1. The problem statement, all variables and given/known dat Three solid spheres of lead, each of mass 9.8 kg, are located at three corners of a square with side lengths of 50 cm. A small object is released at the forth corner. Considering only the gravitational forces among the four objects...

Homework Statement After doing some general solution problems for the force of gravitation on various objects (rods, thin rings, semi-circles, etc), I have noticed that dM varies drastically. For instance on a rod, dM=(M/L)dr while for a semi-circle its (M/2*pi*r)*Rd(theta). I was not able to...

Reading Sean Carol's blog I came across a book that has been made available for free online, Problem Book in Relativity and Gravitation by Lightman, Press, Price, and Teukolsky, http://apps.nrbook.com/relativity/index.html I searched and did not find it mentioned here. If it was mentioned...

The existence of the graviton is repeatedly questioned and surrounded with deep doubts. This affirmation is supported by several elements: The demonstration itself; one get the presumption of that existence via a simplification of the équations of the (generalized) theory of relativity (A...

Hello, few days ago I took an exam in my honors physics class and believe I did not do as well as I did on the other exam. Last exam had a few computational problems and the rest were general solution problems. This recent exam had 8 questions that were all general solution problems as opposed...

Homework Statement For a 0.90km radius cylinder, find the time for one revolution if "gravity" at the surface is to be 9.8 m/s2. Homework Equations rω^2=a The Attempt at a Solution i tried solving for omega but i couldn't find a solution that i only had 1 variable in it.

Homework Statement I am currently reading about Newton's Law of Universal Gravitation and I am so confused as to why there is a negative sign in front of the equation Fg = (G* m1m2)/r^2. Homework Equations Fg = (G* m1m2)/r^2 There is a vector form of the magnitude of the gravitational force...

Homework Statement A particle of mass 3m is located 1.00 m from a particle of mass m. You put a third mass M so that the net gravitational force on M due to the two masses is exactly zero. Is the equilibrium of M at this point stable or unstable for points along the line passing through M and...

Homework Statement Three point particles are fixed in place in the xy plane. The three partiles sit on the corners of an equilateral triangle with sides of length a = 2.50 mm. Particle 1 has a mass m1 = 12.0 kg, particle 2 has a mass m2 = 18.0 kg, and particle 3 has a mass m3 = 15.0 kg. 1...

Homework Statement I'm trying to find the point at which FG attracting to the moon = FG attracting to the earth... 5.98e24 kg = Earth Mass 7.35e22 kg = Moon Mass 3.84e8 m = Distance from Earth to Moon Deductions... a = 3.84e8 - b b = 3.84e8 - a a+b = 3.84e8 Homework Equations g = G m / r2...

Homework Statement What is the gravitational force between Earth and the sun if the Earth has a mass of 5.98 x 10^24 and the sun has a mass of 1.99 x 10^30. The r is (1.5 x 10^11)^2[/B]Homework Equations F=(Gm1m2)/r^2 G= 6.67 x 10^-11 N m^2 /kg^2 ( note that this is a constant)[/B]The...

I was thinking about a situation where we lived in a cubical earth! (Gravity is such that people at each surface will still feel that they are standing upright). I came up with some interesting situations like when a ship crosses an edge or throwing a ball from the edge of surface... What would...

Homework Statement From my book-- "In motion of a planet round the sun we have assumed the mass of the sun to be too large in comparison to the mass of the planet. Under such a situation, the sun remains stationary and the planet revolves round the sun. If, however, masses of sun and planet are...

If a bullet is fired vertically from the surface of the Earth with initial velocity v = 10 km / s, ignoring air resistance, at which distance h from the center of the Earth would arrive? (The radius of the Earth is RT = 6360 km, and the mass of the Earth MT = 5.98x10^24 kg) I used the formula...

I always thought when there is no force acting on an object it moves at constant speed but every object that moves generates gravitational waves what causes that object to lose energy. Does it mean that object loses kinetic energy and slows down and after some (very long) time will stop.

I have a 3-pack of related relativity musings I was hoping someone(s) could enlighten me on: 1) Since the reach of gravity is infinite and the universe is homogeneous and isotropic with regards to the distribution of matter, is it fair to say that no object, even those in deep interstellar or...

Homework Statement There is a tether ball swinging around in a uniform circle on a rope that is 1.90m long. Marcus hit the ball so hard that the string holding the ball made a 20.0 degree angle to the horizontal. What is the tension in the rope if the ball has a mass of 1.40 kg? Assume that the...

Homework Statement Two solid copper spheres of radii 1 and 2 cm are released from rest in free space, their centers being 20 cm apart. Estimate the velocity with which they collide Homework Equations density =mass/volume F=GMm/r^2 The Attempt at a Solution Find mass of each from density of...

In a bosonic atom i.e. Hydrogen, why do we never observe quantum tunneling past the coulomb barrier leading to multiple atoms occupying the same area of space thus (due to Newton's law of universal gravitation) accelerating towards each other resulting in nuclear fusion?

1. An asteroid is 10r away from the earth, and traveling at a speed of 12 km/s. What is the impact speed of the asteroid when it hits the earth?2. Gravitation problem: U = -Gm[E]m / r ...I think3. I've been looking in my book and online and cannot figure it out, please help!

If we travel 100 km vertically from the surface of the earth, will we no longer be pulled by Earth's gravity and float into space? Same question as above yet with 1000 km. How far up vertically do we have to go to escape Earth's pull and how wide/long is the Earth's gravitational influence. Does...

Homework Statement Given that the force of gravitation between Planet A (the one in the left side of the drawing), Fa=3000/da2 and the force of gravitation between Planet B and the rocket, Fb= 6000/ db2. Assuming that the three bodies involved is in stationary. What are the distances (ranges)...

Homework Statement (This is self-study.) In the equation just above 10.27 on page 263 of "Gravitation" by Misner, Thorne, and Wheeler, the first term is: \frac{\partial}{\partial x^{\beta}} (\frac{dx^{\alpha}}{d\lambda}) \frac{dx^{\beta}}{d\lambda} which becomes the first term in (10.27)...

Hi. In class, the professor has tried to derive the equation by using the principle of least-action. (But not yet completed. Maybe next class...) However I heard this method is used by Hilbert, who had derived the equation 5 days before Einstein derived it. Then, what method did Einstein use...

Homework Statement If two bodies, each of mass M and radius R, initially r (r>>>R) distant away from each other start approaching each other with negligible speed then what is their speed which they collide?? Homework Equations The Attempt at a Solution initial energy,IE = (-G m^2) / r final...

Homework Statement The value of acceleration due to gravity at a point P inside the Earth and at another point Q outside the Earth is g/2 (g being acceleration due to gravity at the surface of earth). Maximum possible distance in terms of radius of Earth R between P and Q is Ans: R/2 (...

Homework Statement Use the binomial expansion (1± x)n = 1± nx + (n(n-1)/2) x2 ±... to show that the value of g is altered by approximately Δg ≈ -2g(Δr/rE) at a height Δr above the Earth's surface, where rE is the radius of the Earth, as long as Δr<<rE Homework Equations g=GM/r2 The Attempt...

Homework Statement The acceleration of gravity on the Moon is 1/6 what it is on Earth. The radius of the Moon is 1/4 that of the Earth. What is the Moon's mass compared to the Earth's? Homework Equations F_g = \frac{GMm} {r^2} => mg = \frac{GMm} {r^2} => g = \frac{GM} {r^2} => M = \frac{gr^2}...

Homework Statement An asteroid of mass m = 2.6 × 10^6 kg approaches the Earth. When it is exactly 3 Earth radii away from the Earth's centre its speed relative to the Earth's centre is u = 8.7 × 10^3 m s–1. The asteroid subsequently falls down to the Earth's surface. You may assume that the...

Homework Statement In deriving the expression ##\frac{f'-f}{f}=\frac{gH}{c^2}=\frac{GM_s}{R_sc^2}## , it was assumed that ##\triangle f=f'-f## was small, and that the photon had a constant mass of ##\frac{hf}{c^2}##. Suppose that a star is so dense that ##\triangle f## is not small. (a) Show...

Caution: I'm new at this stuff. On page 573 of Gravitation (Misner, Thorne, Wheeler), they write down what I think is the electromagnetic wave equation for a discussion on Optics, "Next insert the vector potential (22.25) into the source-free wave equation (22.19d):" I am wondering if the...

I have fundamental question about what is called the “law of conservation of energy”. We all hear about the tidal power stations which using the tidal power. The source of the tidal power came from the changes in the gravity field between the moon and the earth. Allegedly, because of the law of...

If f dimensions are ml/t^2, where does t^2 come from in the equation of F = G*m1*m2/r^2 where I believe G to be a constant, m1 and m2 to be masses and r to be the distance between two masses - so length. To dimensionally analyse this then, where would the dimension time come from if I were to...

Homework Statement Suppose two stars are orbiting each other in circular orbits with angular speed ##\omega## .M1 is at distance r1 from CM wheras M2 is at distance r2 such that r1+r2=d where d is the distance between them . Now i have a little doubt whether the stars are orbiting around...

I've been doing research on Le Sage's theory of gravitation, anyone interested in discussing the possibility of "push Gravity"?

What is the nature of the force of gravitation? Is it electrostatic,magnetic or something else? According to the law of gravity.. gravity exists between atoms to planets and planets to supernovae, How does gravitation occur? If possible, don`t paste links of references...just quote them.. I`ll...

Homework Statement At which minimal speed must a stone be thrown from the moon in order to reach earth. R is the Earth's radius and r the moon's. M is the Earth's mass and m the moon's. I ignore the stone's mass, it cancels Homework Equations $$U=-\frac{GMm}{r}$$ G=6.7E-11 R=6.4E6...

Homework Statement A mass m=100[kg] is released from stand still at point A which is in a distance of 1E7[m] from the face of a planet. The planet's radius is also 1E7[m] and the free fall acceleration on it's face is 10[m/s2. What is the acceleration at point A Homework Equations The...

Homework Statement A satellite orbits at radius r1. What is the energy required to pass it to a greater radius r2. express in terms of m and g Homework Equations The total energy of a satellite: ##E=-\frac{GMm}{2r}## The Attempt at a Solution...

Homework Statement A mass m is sent from Earth into an orbit. the period is T. What is the energy required to put it into orbit. express it with T, m, M, R(radius of earth) Homework Equations $$E=\frac{1}{2}mv^2-\frac{GMm}{r}$$ $$2\pi r=vT$$ The Attempt at a Solution I expressed the...

Homework Statement Mass m is left to fall from height h above the surface of a star with radius R. derive an expression for the velocity it hits the ground, using R, h and the acceleration g Homework Equations The energy: ##E=\frac{1}{2}mv^2-\frac{GMm}{r}## The acceleration...

Homework Statement A rocket is shot with velocity smaller than the escape velocity. at what angle to the horizon should it be fired in order to reach maximum height. Homework Equations Total energy: ##E=\frac{1}{2}mv^2-\frac{GMm}{r}## The Attempt at a Solution The equation isn't vectorial, it...