what is mass... dont say something like how much matter something has?

Question

like volume is how much space something takes up.. and weight is how heavy something is!

Answer 1

Mass is a property of a physical object that quantifies the amount of matter AND energy it is equivalent to.

I know you don't want matter mentioned, but the way you limited it is a bit like asking, "What is CO2? But don't say Carbon Dioxide." But out of respect for your wishes, I did the best I could.

Mass is a central concept of classical mechanics and related subjects, and there are several forms of mass within the framework of relativistic kinematics (see mass in special relativity and mass in General Relativity). In the theory of relativity, the quantity invariant mass, which in concept is close to the classical idea of mass, does not vary between single observers in different reference frames.

There are three types of mass or properties called mass:

1) Inertial mass is a measure of an object's resistance to changing its state of motion when a force is applied. An object with small inertial mass changes its motion more readily, and an object with large inertial mass does so less readily.
2) Passive gravitational mass is a measure of the strength of an object's interaction with the gravitational field. Within the same gravitational field, an object with a smaller passive gravitational mass experiences a smaller force than an object with a larger passive gravitational mass. (This force is called the weight of the object. In informal usage, the word "weight" is often used synonymously with "mass", because the strength of the gravitational field is roughly constant everywhere on the surface of the Earth. In physics, the two terms are distinct: an object will have a larger weight if it is placed in a stronger gravitational field, but its passive gravitational mass remains unchanged.)
3) Active gravitational mass is a measure of the strength of the gravitational field due to a particular object. For example, the gravitational field that one experiences on the Moon is weaker than that of the Earth because the Moon has less active gravitational mass.

Although inertial mass, passive gravitational mass and active gravitational mass are conceptually distinct, no experiment has ever unambiguously demonstrated any difference between them.

One of the consequences of the equivalence of inertial mass and passive gravitational mass is the fact, famously demonstrated by Galileo Galilei, that objects with different masses fall at the same rate, assuming factors like air resistance are negligible. The theory of general relativity, the most accurate theory of gravitation known to physicists to date, rests on the assumption that inertial and passive gravitational mass are completely equivalent. This is known as the weak equivalence principle. Classically, active and passive gravitational mass were equivalent as a consequence of Newton's third law, but a new axiom is required in the context of relativity's reformulation of gravity and mechanics. Thus, standard general relativity also assumes the equivalence of inertial mass and active gravitational mass; this equivalence is sometimes called the strong equivalence principle.

If one were to treat inertial mass mi, passive gravitational mass mp, and active gravitational mass ma distinctly, Newton's law of universal gravitation would give as force on the second mass due to the first mass.


Newton's third law, of reciprocal actions, shows that active and passive mass are proportional. As a result they can be defined to be equal.

Mass has nothing to do with density. A tone of feathers has the exact same mass as a ton of bricks.

Weight isn't a good definiton of mass because weight is relative. An object weighed on the moon would weigh less than it would on earth, but its mass wouldn't have changed.

Answer 2

Mass is a place Catholics go on Sunday.
It is also a large amount of energy. Einstein showed that mass and energy are really the same thing by "E=MC (squared)".
Mass has weight when it is touched by acceleration. Even energy has weight since it is affected by large masses which causes it to change its path of travel. When light from a distance star passes near the sun, the sun causes the light to distort and not go straight anymore.
For our purposes on earth, if you put something on a scale and the needle moves, then the object has mass making it up. If you could look into a microscope with infinite power, you'd see atoms making up the object. Most of the inside of atoms is empty space.
The total universe is in the process of expansion. All atoms are expanding outward. Everything every where is expanding. The surface of the earth is expanding. Your body is expanding. You can feel the earth expanding because the surface is rising up as you stand on it. We call this gravity. When you get in an elevator and it rises it feels like gravity is increasing, but it's just the bottom of the elevator moving upwards, just like the surface of the earth is.

Answer 3

Mass is the property of an object that makes it resist acceleration and determines how much gravitational pull it experiences.

Answer 4

imagining that you are NOT talking about relativiry, mass really is how heavy "stuff" is. kilograms, pounds, tonnes are used to measure mass like litres are used to measure volume

(in relativity it gets much more complicated, because mass and energy of an object are relative to each other)

Answer 5

Mass is also similar to weight.

In the SI system of units, mass is measured in kilograms (kg).

Answer 6

How much matter AND how densely packed it is!

Answer 7

All right, I won't say that.