What is Gravitation: Definition and 914 Discussions
Gravity (from Latin gravitas 'weight'), or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are attracted to (or gravitate toward) one another. On Earth, gravity gives weight to physical objects, and the Moon's gravity causes the ocean tides. The gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing and forming stars and caused the stars to group together into galaxies, so gravity is responsible for many of the large-scale structures in the Universe. Gravity has an infinite range, although its effects become weaker as objects get further away.
Gravity is most accurately described by the general theory of relativity (proposed by Albert Einstein in 1915), which describes gravity not as a force, but as a consequence of masses moving along geodesic lines in a curved spacetime caused by the uneven distribution of mass. The most extreme example of this curvature of spacetime is a black hole, from which nothing—not even light—can escape once past the black hole's event horizon. However, for most applications, gravity is well approximated by Newton's law of universal gravitation, which describes gravity as a force causing any two bodies to be attracted toward each other, with magnitude proportional to the product of their masses and inversely proportional to the square of the distance between them.
Gravity is the weakest of the four fundamental interactions of physics, approximately 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a consequence, it has no significant influence at the level of subatomic particles. In contrast, it is the dominant interaction at the macroscopic scale, and is the cause of the formation, shape and trajectory (orbit) of astronomical bodies.
Current models of particle physics imply that the earliest instance of gravity in the Universe, possibly in the form of quantum gravity, supergravity or a gravitational singularity, along with ordinary space and time, developed during the Planck epoch (up to 10−43 seconds after the birth of the Universe), possibly from a primeval state, such as a false vacuum, quantum vacuum or virtual particle, in a currently unknown manner. Attempts to develop a theory of gravity consistent with quantum mechanics, a quantum gravity theory, which would allow gravity to be united in a common mathematical framework (a theory of everything) with the other three fundamental interactions of physics, are a current area of research.
I am struggling to understand Newtons law:
F = ma = GMm/r^2
a = GM/r^2
In the above equation, the small m's cancel out to give a constant acceleration due to gravity from the perspective of big M. I consider a planet and a small moon (little m) a certain distance away from the planet...
Homework Statement
Transplanertay tours promises tour participants a certificate to commemorate their passage from the stronger influence of Earth's graviational pull to the stronger pull of the Moon at the point where the two forces on your spaceship are equal. Where on the trip should you...
Homework Statement
During a solar eclipse, the Moon, the Earth, and the Sun all lie on the same line, with the Moon between the Earth and the Sun. (a) What force is exerted by the sun on the moon? (b) What force is exerted by the Earth on the Moon? (c) What force is exerted by the sun on the...
Homework Statement
A satellite of mass 4600 kg orbits the Earth (mass = 6.0 1024 kg) and has a period of 5500 s.
(a) Find the magnitude of the Earth's gravitational force on the satellite.
(b) Find the altitude of the satelite
Homework Equations
Kepler's Equation: R^3/T^2
Fg=...
A satellite is in a circular Earth orbit of radius r. The area A enclosed by the orbit depends on r2 because A = πr2. Determine how the following properties of the satellite depend on r. In each case, give the power of r, i.e., if the dependence goes as rn, give n. If there is no dependence...
Homework Statement
A satellite in a circular orbit around the Earth with a radius 1.021 times the mean radius of the Earth is hit by an incoming meteorite. A large fragment (m = 65 kg) is ejected in the backwards direction so that it is stationary with respect to the Earth and falls directly...
Homework Statement
What force does Earth exert on a 80.0-kg astronaut at an altitude equivalent to 2.5 times Earth's radius?
Homework Equations
FG = (Gm1m2) / r2
Radius of Earth: 6370 km
Mass of Earth: 5.97x1024 kg
The Attempt at a Solution
FG = (Gm1m2) / r2
FG = (G x MEarth x 80...
First off this is not homework or coursework, just general interest.
I've been looking to derive the rocket equation which includes the effects of Universal Gravitation. I've been able to derive it assuming near Earth gravity where g is taking as constant acceleration...
General relativity predicts that electromagnetic fields contribute to the stress-energy tensor, and that they therefore have gravitational fields. Kreuzer (1968) did laboratory experiments that were interpreted by Will (1976) as confirmation of this prediction in the case of the static electric...
Homework Statement
Let a particle slides in a straight smooth tube passing obliquely through the Earth. Assuming no friction and no rotational effects. Describe the motion. Find Frequency and Period.
Homework Equations
F = -GMm/r^2
The Attempt at a Solution
Don't know how to...
Gravitation and Electromagnetic forces are independent, correct? That implies.. Gravitation would exist even if Electromagnetic forces didn't. But, electromagnetic forces are responsible for existence of atoms.. and atoms are what make up the mass, no? And Gravitation exists because of Mass...
I'm a math major, but I really want to learn about general relativity (the 'real' GR, not the watered-down version that gets into popular science books) on my own. I'm not in any rush to learn it--i.e., I'm willing to work through a big tome like Gravitation over the course of, say, the next...
A skier lowers a cart 30m down a slope with a sontant speed. The cart has a mass of 90kg. The angle of the slope is 60 degrees. The coefficient of friction is 0.100.
A)Find the work done by friction as the sled moves down the hill.
B) how much work is done by the rope on the sled.
C) What is...
3 10 kg spheres are located at the corners of a equilateral triangle of sides .5m. Calculate the magnitude of the total gravitational force exerted on one sphere by the other two.
I used G = 6.67 x 10^-11.
The answer I got was 4.62 x 10 ^-8. Can anyone confirm if this is correct, or explain how...
Homework Statement
An artificial satellite of mass m of a planet of mass M, revolves in a circular orbit whose radius is n times the radius R of the planet. In the process of motion, the satellite experiences a slight resistance due to cosmic dust. Assuming the resistive force on satellite...
Homework Statement
2 particles of masses M and m are initially at rest and infinitely separated. When they move towards each other due to gravitational attraction, what is their relative velocity at any instant?
Homework Equations
The Attempt at a Solution
The problem may be...
Homework Statement
A particle is projected from the surface of the Earth with an initial speed of 4km/s. Find the max. height attained by the particle. Radius of Earth = 6400 km and g=9.8 m/s2
Homework Equations
The Attempt at a Solution
I have two approaches to this problem...
HI,
I am new in this kind of programming ..this is my very first 2D game in OpenGl using Glut 3.7 (Win32 Console C++) and i have no idea how to apply projectile motion and gravitation on basket ball.
game is simple.. Inputs Are Force and Angle.. and player has to throw the ball into the...
I apologize for my English, it's not my native language.
Homework Statement
There's three masses of 1 kg each set in an equilateral triangle of side length 0.8 meters. Mass m1 is located in coordinates (-0.4m, 0) and m2 is located in coordinates (0.4m, 0). What are the coordinates of m3?
A...
How do we know that light travels on null geodesic in arbitrary curved spacetime.
Could anyone give me reason for this assumption (many GR textbooks assume
this without any justification).
In flat space time the above fact may be proven by means of the Green function.
It tells us that the...
I received this problem this week and no one in my class has been able to solve it. We don't need to solve it exactly, but we should provide a conceptual answer. I would really appreciate it if anyone could help me out.
-The apparent weight of a person may vary in different latitudes due to...
Homework Statement
Consider a hypothetical extra*solar world, planet X, that has 2.2 times the radius of the Earth and 2.5 times its density.
What is the acceleration due to gravity on the surface of planet X?
Homework Equations
g=GM/r^2
The Attempt at a Solution
I am not...
Hello, could you please help to clarifly the following.
Do electromagnetic (e.g. light) and gravitational wavefronts caused by e.g. a supernova both appear at the same time seen from a distant observer perspective?
Thank you!
While reading gravitation chapter I got some doubts, and that I am posting here.
1) Is there any meaning of "Weight of the Earth"?
2)At noon, the sun and the Earth pull the objects on the Earth's surface in opposite direction. At midnight the sun and the Earth pull these objects in the...
Homework Statement
I am doing a lab-"Kepler's Laws and Newton's Law of Universal Gravitation". There is an image representing various positions, at equal intervals, of a satelitte in an elliptical orbit around the earth. A list of planets and their radi and periods are given. I have calculated...
Hi all, this will be my first physics qns:D more to come...
I just learned that value of g at the equator is not exactly equal to the gravitational field strength. Can anyone explain with workings? i don't really understand my teacher workings.
Also can i clarify if
-We're assuming Earth...
1. Take the equation F=[G(m1)(m2)]/r2
2. Assume a single mass of 20 (units don't matter), which will be divided in the following ways:
2.1. System 1: m1=20, m2=0
2.2. System 2: m1=19, m2=1
2.3. System 3: m1=18, m2=2
2.4. System 4: m1=17, m2=3
.
.
.
2.11.System 11: m1=10, m2=10
Now...
3...
Homework Statement
The average distance separating Earth and the moon is 384000km. What is the net gravitational force exerted by Earth and the moon on a 3.00 x 10^4kg spaceship located halfway between them.
Homework Equations
F=Gm1m2/r^2
G = 6.673x10^-11
earth mass = 5.98x10^24...
At the very bottom of the page they have that the straight line, using the definition of a vector as the derivative of the worldline is given as:
P(0) + \lambda(\frac{dP}{d\tau})_o
But since the worldline, P(\tau) is paramtrized by \tau and not \lambda, then shouldn't the equation be...
Homework Statement
At a certain point between Earth and the Moon, the net gravitational force exerted on an object by the Earth and the Moon is ZERO. The mass of the Moon is 1.2% the Mass of the Earth. The centre to centre distance between the Moon and the Earth is 3.84*10^5 km.
i) WHERE IS...
HI,
According to GR, gravitation is simply the geometry bending. Does this also apply on Earth? We can stick on Earth, does it the force attract us?? Or is a geometry problem as well??
I get confused about this.
Thanks
Alex
Homework Statement
Say, there are two bodies, mass m1 and m2, initially at rest at infinite separation. They start accelerating towards each other because of gravity. Express the relative velocity of approach as a function of the distance between the two bodies.
Homework Equations
Laws...
Homework Statement
Two objects attract each other with a gravitational magnitude 1.00x10-8N when separated by 20.0cm. If the total mass of the two objects is 5.00kg what is the mass of each?
Homework Equations
Fg=G*m1m2/r2
G=6.673x10-11Nm2/kg2
I'm not real sure how to go about this...
In the example 12.5 (Section 12.3) in the textbook we ignored the gravitational effects of the moon on a spacecraft en route from the Earth to the moon. In fact, we must include the gravitational potential energy due to the moon as well. For this problem, you can ignore the motion of the Earth...
Hi Guys I am in year 12 and have my exam shortly would just like to ask a question to do with gravity.
A small satellite orbits Mars. It has a kinetic energy of 3.0x10^10 J, and is at a constant distance of 8.0x10^7 m from the center of Mars. What is the weight of the satellite at this height?
Okay, this is going to be one hell of a skeptical thread.
Being a musician and all i have music software that enables me to manipulate sound
As of now, I've manipulated a Bass note in C to a harmonic oscillation(sp?) ranging from >0hz to 500hz. I've got it just to were the noise won't...
Homework Statement
At what height will the acceleration due to gravity will fall to 25% that of the Earth's surface?
Homework Equations
g= GM/R^2
The Attempt at a Solution
gravitation lab for online simulation--equation derivation help?
Homework Statement
To start with, you can access the lab here: http://phet.colorado.edu/teacher_ideas/view-contribution.php?contribution_id=690" .
I'm having trouble with the "Activity 4" part. It reads:
"Change the number of...
Homework Statement
A spaceship is launched and starts moving directly towards the Moon. At what distance from the Earth will the pull of the Moon, on the spaceship, exceed the pull of the Earth? Ignore the effect of the sun in this calculation.
Homework Equations
F=G(M1M2/r^2)
The Attempt...
On the full moon day the moon is closer to Earth so the gravitation of the moon make the gravitation of the Earth on us less strong.
Is it true ?
Thanks !
Homework Statement
What is the kinetic energy and total mechanical energy of a binary system of identical spheres orbiting around their common center of mass?
M = mass
R = radius
Homework Equations
Force of gravity = GM^2/2R
K = 1/2MV^2
The Attempt at a Solution
I don't know whether...
Hey!
My teacher told me that there is a correction term to Newtons law of gravitation when you take general relativity into account, somthing lik:
F=G\frac{M_1M_2}{r^2}+F_{correction}
I been searching like mad but can't find it on the internet anywhere. The only things I found was a set of...
Being possibly the newest member here, I would like to put a question that has troubled my mind for quite a while..
If I have a uniform ring (having a certain mass) and a point mass in some idealised gravity free space & I orient them such that the point mass lies exactly at center of the...
Homework Statement
A small package is fired off Earth's surface with an unknown launch speed, but with a known launch angle of 51.0 as measured from the local horizontal. It reaches a maximum height above the surface of 6380.0 km, a value equal to Earth's radius itself. What is its speed when...
Greetings everyone,
I am a first time poster. I suppose that my initial post will be slightly non-scientific.
This question would seem to to be related to the question asking "Does some event happen if no one is there to observe the happening?"
If the contents of the universe consisted of...