Why does mass cause gravity ?
78675
The poster before me gave an excellent answer which is that nobody really knows. I just wanted to point you to a very cool experiment about how mass warps space.\n\nAnother very profound question to ask would be why are gravitational mass and inetial mass so nearly (if not exactly) equal?
157319
I'm interested in what kind of answers you'll get to this question.  The fact of the matter is, no one really knows what gravity is or where it gets it's energy from.  One of the few things that are known about gravity is that it is not effect by space and time like light.
51910
Weight is a force, but when something is weighed you actually measure it's mass assuming you are in an environment in which the force of gravity is constant (i.e., you're at a fixed location <radius from the center> on a planet or massive planetary mass).\n\nof course, one's mass can be approximated by W=mg at fixed radii from such planetary masses (like the earth, a massive asteroid, a superdense star, whatever...) if the force of gravity, g, is known at that radius.\n\nThere are 2 possible variables here - mass and the force of gravity.  Which one do you know?  usually an approximation for g is given.  Which one do you measure, then...that would be mass.
262021
As the mass increases so does the gravity. A spherical object is shaped this way because of its gravity. The larger the sphere gets the smaller the curvature of its surface becomes. It is related but curvature is more of a side effect of a large rotating object. Gravity is dependant upon the mass of the object not the curvature of it.
87660
Any matter with mass also has the property of gravity. There are two basic schools of thought about what gravity itself is. One idea is that the attractive properties of gravity result from two or more chunks of matter exchanging an elementary particle called the "graviton." One example would be the gravitational attraction between the Earth and the Moon---each planet exchanges gravitons. So far, these graviton particles have not been observed.\n\nAnother idea, this one from Einstein's theory of relativity, says that matter (mass) actually bends the fabric of space, sort of like what would happen if you placed a bowling ball on a sheet of thin rubber. The resulting deformation of space by mass results in other objects to follow the shape of the deformed space. In the Earth/Moon example, the Moon orbits around Earth because it's simply following the shape of the wrinkle in space made by Earth's mass.
247359
Mass interacting with gravity
801793
and gravity does what?\n\nand why don't you fall off?
57362
Weight is a unit measure of gravitational force.
842967
Gravity is a condition of the space-time continuum which is associated with mass.  Every object which has a mass will have a gravitational attraction to any other close object with a mass.\n\nThe planet Earth has a mass, and therefore has a "gravity."
877563
The actual origin of gravity is still a mystery to physicists. Yes, everything with mass has gravity, but that doesn't explain where it actually comes from. The current hypothesis is that gravity originates from a hypothetical particle called the "Higgs boson", which hasn't yet been observed. Physicists hope that the Large Hadron Collider at CERN (Switzerland) will be able to detect it soon.
279317
gravity.\n\nany shape of mass that is not spherical is gravitationally unstable
778402
Mass is a property of matter, it is related to its bulk; how much stuff there is. Weight is the result of a mass subjected to an acceleration, usually the gravity of a planet.  How much gravity a planet gives is a function of its mass, so smaller planet or moons will make you feel lighter (less weight) despite your constant mas.  Also, if you are in orbit, in what is called micro-gravity or free fall, you can even stop feeling any acceleration at all, hence you are weightless, but not massless. In space, you could move very large objects as they have no weight, but you could only move them slowly as your force is limited, and the mass of the object is still there.\nWeight is in direct proportion of the mass of the object attracting you, an in inverse square proportion of how far away one is from the object.\n\nThink of it as pushing a car on neutral on a flat road.  How come it takes so much strength?  Because the car has mass.  In this case, its weight is irrelevant as it it entirely supported by the wheels. But the bulk remains.  Here, the weight manifest itself by hom much compressed the tire and suspension components are squeezed.\nYou can also envision a large ship.  Again, its weight is balanced by the buoyancy of the water -- the weight determines how deep the ship sits in the water.  But try to put it in motion (you have a rope attached to it, and you are on land pulling), and that will take a lot of force.  Sure the ship will move, but that would be very slowly, because the mass of the ship is so great.
1139481
It is the results of Einsteins work on relativity. Einsteins showed gravity cause space-time to warp which will affect how objects interact with each other. Newton explained gravity as the attraction one object has for another, Einsteins theory's have made up for some of newton's short falls, such as Mercury's orbit which doesn't stay the same each time changes with each orbit. Newton laws don't account for this change but Einsteins theory's predict these changes exactly. Theory's of Space-Time were never design to explain the Ether.
890055
Mass is measured in grams etc and is how heavy something is when no force is acting upon it.\n\nWeight is the amount of mass * gravity and should be measured in newtons.  \n\nYour mass can never change, but your weight can depending on how strong gravity is.  Eg on the moon gravity is about x5 weaker than earth, as a result you weigh x5 less than you do on earth.
979053
Mass is always mass in any situation. You can´t change the mass, you only can change some properties of the mass, such as, weight (according the gravity), quantity of cinetic energy (accordind the velocity of the mass), etc. But the mass is always the same mass!!!
709561
An object has mass regardless of gravity.  Gravity gives us 'weight' by placing force on the mass.\n\nSo, strictly speaking, an object's "mass" is a measure of how much matter it contains.  An object's "weight" is a measure of gravity's effect on that object.\n\nSo an object's mass doesn't change if it is on a different planet, but its weight will.
468240
Mass is a direct measure of an object's inertia, and the strength of its gravitational pull. More often, we find it easier to say that mass is a measure of quantity. More mass = more interia, so it works out.\n\nWeight, the way we think of it, is a measure of the net downward force an object undergoes when placed in a gravitational field ("down" meaning toward the source of the gravitational force in question). On Earth, weight is a measure of the effect gravity has on an object.\n\nSince more mass = more for gravity to pull, objects with more mass also have more weight (at the same location in the same gravity field), so we generally use weight and mass interchangeably, and this doesn't cause too many problems.