What is Gravitation: Definition and 913 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 was wondering what is happening with Earth accumulating dust and other debris from outer space? This must change earth’s weight? What is the rate of this accumulation of weight? The same thing must be happening to the sun, surely in proportion to the gravity field of the sun, so probably all...
Homework Statement
A planet around a star has an orbit that is not exactly an ellipse. In addition to the dominant Fo \alpha r^-2 term due to gravity from the central star, the planet seems to be responding to a slight additional force which has the form F1 \alpha r^-\alpha where \alpha...
I was thinking about Newtons law and come across something interesting. F=ma=GMm/r^2
therefore a=GM/r^2. This is the acceleration of the satellite towards the larger mass. But this acceleration is only accurate assuming that the larger mass is stationary. But f=Ma=GMm/r^2, so there is an...
1) In 2004 astronomers reported the discovery of a large Jupiter-sized planet orbiting very close to the star HD 179949 (hence the term "hot Jupiter"). The orbit was just 1/9 the distance of Mercury from our sun, and it takes the planet only 3.09 days to make one orbit (assumed to be circular)...
Homework Statement
2 objects each with mass, m, and radius, r, are unaffected by any other objects. They are the distance L apart. At time t=0 , both are at rest. From then on they accelerate towards each other.
Determine the speed of the planets at the moment of collision.
Homework...
Why is Einstein's law of gravitation for empty space sometimes identified as Ricci tensor=0 instead of Einstein tensor=0. The first condition implies the second one, but not the other way around.
Two spheres are released from rest when the distance between their centers is 12R. Sphere 1 has mass M and radii R while sphere 2 has mass 2M and radii 3R. How fast will each sphere be moving when they collide? Assume that the two spheres interact only with each other. (Use G for gravitational...
[SOLVED] need help with gravitation conservation of energy problem
Homework Statement
Zero, a hypothetical planet, has a mass of 2.0E23 kg, a radius of 3.0E6 m, and no atmosphere. A 17 kg space probe is to be launched vertically from its surface.
(a) If the probe is launched with an initial...
[SOLVED] Need Help on Gravitation Potential Energy Problem
Homework Statement
(a) A 5.3 kg particle and a 3.0 kg particle have a gravitational attraction with a magnitude of 2.6 x10^-12 N. What is the gravitational potential energy of the two-particle system?
(b) If you triple the...
Homework Statement
One dimension. In Fig. 13-33, two point particles are fixed on an x-axis separated by distance d. Particle A has mass mA and particle B has mass 7.00 mA. A third particle C, of mass 75.0 mA, is to be placed on the x-axis and near particles A and B. In terms of distance d, at...
Homework Statement
What is the ratio of the gravitationalpull of the sun on the moon to that of the Earth on the moon?(Assume the distance of the moon from the suncan be approximated by the distance of the Earth from the sun.)
Homework Equations
F_{g} =...
Homework Statement
Determine the magnitude of the force of gravity acting on a 340 kg satellite, 850km above Earth's surface.
Homework Equations
So I dedcided to use the Universal Gravitation Law:
Fg = (Gm1m2)/d^2
The Attempt at a Solution
m1=5.98E24 (earth's mass)
m2=340kg...
[SOLVED] Gravitation Problem
Homework Statement
The moon has a mass of 7.7times10^22kg and radius 1.7times10^6m. Calculate:
a) The gravitational potential at its surface.
b) The work needed to completely remove a 1.5times10^3kg spacecraft from its surface into outer space.
c) What is the...
Homework Statement
A synchronous satellite, which always remains above the same point on a planet's wquator, is put in orbit around Jupiter to study the famous red spot. Jupiter rotates once every 9.84 h. find the altitude of the satelite
Homework Equations
jupiter: mass in kg...
Here is the homepage of the event -- to be held from Jun 19 to Jul 05 2008, in João Pessoa, Brazil:
http://www.fisica.ufpb.br/eventos/friedmann2008/friedmann2008new2.htm
http://www.fisica.ufpb.br/eventos/friedmann2008/friedmann2008new2_arquivos/page0016.htm" are the current scheduled...
[SOLVED] magnetic plus gravitation force
Homework Statement
A circuit consists of wires at the top and bottom and identical metal springs in the left and right sides. the upper portion of the circuit is fixed and has a 24 v battery and 12 ohm resistance. the wire at the bottom has a mass...
[SOLVED] Gravitation Force Using Differentials
Homework Statement
Three part question:
1. Consider a solar system similar to our Sun and Earth, where the mass and radius of the planet are 4.22e24 kg and 6.63e6 m, respectively, the mass of the sun is 2.08e30 kg and the planet-sun...
After doing some playing around with area lights in raytracing, I realized that the shape of the emitter has a lot to do with the intensity falloff rate (when the "photons" are always emitted in a direction normal to the surface).
ex: A spherical emitter's field falls off with 1/r^2, a...
Hi everyone,
Could someone please help me on this problem?
Homework Statement
Newton's law of universal gravitation is represented by the following equation where F is the magnitude of the gravitational force exerted by one small object on another, M and m are the masses of the...
So I'm reading "Mathematical Physics" by Donald H.
Menzel, and I don't buy the following derivation from
section 2.12
The purpose of the derivation is derive the potential
energy at a point Po which is a distance Ro from the
center of a sphere of uniform density.
First they...
Homework Statement Your starship, the Aimless Wanderer, lands on the mysterious planet Mongo. As chief scientist-engineer, you make the following measurements: a 2.50-kg stone thrown upward from the ground at 11.0 returns to the ground in 9.00 ; the circumference of Mongo at the equator is...
Just a question about gravitation equations:
Neglecting Earth's rotation, show that the energy needed to launch a satellite of mass m into circular orbit at altitude h is equal to:
(\frac {GMm}{R})(\frac{R+2h}{2(R+h)})
Where R = the radius of the Earth and M = the mass of the Earth...
Just a question about gravitation equations:
Neglecting Earth's rotation, show that the energy needed to launch a satellite of mass m into circular orbit at altitude h is equal to:
(\frac {GMm}{R})(\frac{R+2h}{2(R+h)})
Where R = the radius of the Earth and M = the mass of the Earth...
[SOLVED] Gravitation & Escape Speed - Stone leaving Earth and reached the Moon.
Hello everyone, I have one question on gravitation and escape speed. In the earlier part of the question, the minimum speed for the stone to leave the Earth is calculated and its final destination is the Moon...
[SOLVED] Law of gravitation
In Figure 13-34, a square of edge length 15.0 cm is formed by four spheres of masses m1 = 5.00 g, m2 = 4.00 g, m3 = 1.50 g, and m4 = 5.00 g. In unit-vector notation, what is the net gravitational force from them on a central sphere with mass m5 = 2.10 g?
I know...
1. A planet has a mass 1/2 that of Earth and a radius 2 times that of Earth. What is the acceleration due to gravity on the surface of the planet in terms of g?
2.
a)F=G*m1*m2/r^{2}
b)F=mg
3. I figured that I would let the two equations equal to each other so...
Homework Statement
The gravitational force between two shperes is 2.50x10^-8. Their centers are 105 cm apart. The larger sphere has a mass of 8.20 kg. Find the mass of the smaller sphere.
Homework Equations
F=Gm1m2/d²
The Attempt at a Solution
F=Gm1m2/d²
d² x F=Gm1m2/d² x d²...
Homework Statement
Zero, a hypothetical planet, has a mass of 5.0*10^23 kg, a radius of 3.0*10^6m, and no atmosphere. A 10kg space probe is to be launched vertically from its surface. (a) If the probe is launched with an initial energy of 5.0*10^7 J, what will its kinetic energy be when it is...
[SOLVED] Universal Gravitation
Homework Statement
A small rocket is launched vertically, attaining a maximum speed at burnout of 1.0x10^2 m/s and thereafter coasting straight up to a maximum altitude of 1519 m. Assuming the rocket accelerated uniformly while the engine was on, how long did it...
Neutron stars are extremely dense objects that are formed from the remnants of supernova explosions. Many rotate very rapidly. Suppose that the mass of a certain spherical neutron star is twice the mass of the Sun and its radius is 5.0 km. Determine the greatest possible angular speed it can...
Gravitation Problem :(
Question:
Find the point between Earth and the sun at which an object can be placed so that the net gravitational force exerted by Earth and the sun on an object is zero.
Earth's mass: 5.98x10^24 kg
Earth's radius: 6.38x10^6 m
Sun's mass: 1.991x10^30 kg
Sun's...
Suppose one is not happy with Newton's law of gravitation and finds that it should be modified and that one has an equation describing the gravitational potential
\phi in function of radius. If one then want to obtain a relativistic description, would it be sufficient to replace in the...
Homework Statement
Two equal-mass stars maintain a constant distance apart of 8.0 x10^10 m and rotate about a point midway between them at a rate of one revolution every 12.6 yr
(a) why don't the two stars crash into one another due to the gravitational force between them
(b) what must be...
1. Two satellites are orbiting around Earth. One satellite has a period of 1.4hours and
is 200km above Earths surface. The other satellite has a period of 6.0h. Use Kepler's laws
and the fact the radius of Earth is 6.37 x 10^6meters to determine the height of the second satellite above Earths...
http://arxiv.org/abs/0711.2274
The cosmological constant is claimed to be tamed and computable.
Curious...
"The Poincare' group generalizes the Galilei group for high-velocity
kinematics. The de Sitter group is here assumed to go one step
further, generalizing Poincare' as the group governing...
1. An evacuated box is at rest on a frictionless table. You punch a small hole in one face so that air can enter. How will the box move?
I figure the box will move in the direction opposite that of the hole, the centre of mass will shift in the direction and air will rush into fill the...
A tunnel is bored through the center of a planet, as shown in the Figure (this drawing is NOT to scale and the size of the tunnel is extremely exaggerated). Assume that the planet is a homogenous sphere with a total mass M = 3.6 × 1024 kg and a radius R = 7300 km. A package of mass m = 7.8 kg is...
1. A block slides along a track with elevated ends. The flat part has length L = 0.2m, and the object is released from a height of 0.1m. The curved portion of the track is frictionless, but the flat part has uk = 0.15 . where does the object finally come to rest?
Etotal = Ui + Ki = Uf +...
1.
A 55.5 kg skateboarder starts out with a speed of 1.75 m/s. He does +80.0 J of work on himself by pushing with his feet against the ground. In addition, friction does -265 J of work on him. In both cases, the forces doing the work are nonconservative. The final speed of the skateboarder is...
Homework Statement
How far from Earth must a space prove be along a line toward the Sun, so that that the Sun's gravitational pull on the probe balances the Earth's pull
Homework Equations
F=Gm1m2/d^2
The Attempt at a Solution
d1=distance from probe to Earth
distance from sun to...
Homework Statement
A mass M is split into two parts, m and M - m, which are then separated by a certain distance. What ratio m/M maximizes the magnitude of the gravitational force between the parts?
Homework Equations
F=Gm1m2/d^2
The Attempt at a Solution
I first just tried plugging...
I am having trouble solving this problem:
Three point particles are fixed in position in an xy plane. Two of them, particle A of mass 6.00g and particle B of mass 12.0g, are shown in Fig12-38 (the figure has A at the origin and B 30 degrees above the negative side of the x-axis) with a...
Homework Statement
A student proposes to measure the gravitational constant G by suspending two spherical objects from the ceiling of a tall cathedral and measuring the deflection of the cables from the vertical. If two 155.0 kg objects are suspended at the lower ends of cables 40.00 m long...
[SOLVED] Physics Probs
HI there!:cool:
Can u just give some more ideas and explanation on Gravitation,Upthrust,
Buoyancy?:confused:
Some numericals to explain n to add on would b better.:smile:
"Consider the Earth following its nearly circular orbit about the sun. The Earth has a mass mearth=5.98x10^24kg and the sun has mass msu=1.99x10^30kg. They are separated, center to center, by r=93 million miles = 150 million km."
What is the size of the gravitational force acting on the Earth...
Hi I like to know,
Why there are gravitation at all which make every matter in our daily life can attract each other? such as Earth with moon, sun with earth, Earth with human, and so on. I've searched in many source even e-source(internet source), many physics books, professor in...