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But you don't know what force is.
Classically, we think of it as the quantity of matter we have. Using a balance scale, we can say whether two lumps of matter A and B, have the same amount of mass. And then we can define an absolute scale by saying that a certain amount of a given material is 1 kg or 1 g or 1 whatever-unit-of-mass-you-like. This is until recently how 1 kg was defined, with a standard piece of metal kept in a lab in France.
We define force as ma so you can't define m as f/m
But why did we define mass?
because it is an exceedingly useful concept!
No I mean what made us define mass?What did we need it for in the first place
For basic economic transactions: "I want ten bags of full rice for that pig. Wait, these bags aren't full, they don't weigh enough."
So what is it a measure of?
And for construction as well. I'm sure it was very quickly apparent to early humans that understanding the mass of wood and blocks of stone was critical. ...Like I said above, it is a measure of the amount of matter we have in front of us.
So how would you measure the mass of something?
By putting it on a balance scale and comparing it to a set of standard measures. Or putting it on a spring mass, and seeing how far it depresses the spring.
But there you are using gravity which is inturn using f=ma.I mean without earth or any thing measure mass of a body
For the record, F = ma is NOT the definition of force. It is a relationship with force satisfies. So there's no reason not to use F in helping us understand and measure m.
Well,alright then you don't know what force is so now measure mass
What is mass? it is a question that has got scientists struggling for centuries, until recently it has only been accepted as a property of all objects, starting from the tiniest building blocks of matter, the elemental particles all have a certain quantity of mass, you may see it as the amount of matter as well, but then elemental particles adopt bizarre almost random values differing enormously in each case, where the large ones are light compared to the smallest which are incoherently the heaviest. The latest theories suggest that mass comes from a thing called Higgs field, this hasn't been discovered or confirmed yet, but explains that mass derives from the "friction" between the particles and this field which is everywhere, each particle has a different mass because they pass through this field in a particular way that is related to their other properties. So if a particle is more reactive to the Higgs field it has more mass and therefore stronger force.
But what did we start of with?I mean we used the concept of mass even before all of that right.
we started by declaring mass as literally "how many things are in there" you can count it, but then each of these "things" has to be equal to any other "thing", these things have to be the absolute smallest or most elemental things, I mean they cant be made up of other things, they are on the limit, no less can be.
So what is the difference between numbers and mass?
in classical physics nothing, mass is the number of "elemental things" there are. You can actually count them, if in one object you count 5 things and in another 10 things, the first object has half the mass of the other. Simple as that, but then remember this is in classical physics.
wow great and intersting question. Why did we define mass... I guess that people and scientists were looking at matter and studying matter. They saw two qualties of matter that made them think of the concept of mass. One is Inertia some bodies are harder to moce (accelrate) or harder to stop and some are easy to stop or accelerate. So they came up with a name Mass - a measure for Inertia! The second quality is gravity, every two bodies attract each with some force, that can be big or small, but bodies with great inertia also pull strongly, so the concept of mass is usefull again! Mass - a measure for the gravtional field a body creates. It is not obvious at all that the Inertia, and Gravity of a body can be well defined by the same measure, but it is (luckily) Tnx for the nice question! sorry for bad spelling
So how do you measure the mass of something by itself and not using any other physical quantities.
Here you can see that it is about energy, Inertia is referring to kinetic energy, some objects are harder to move because they have more kinetic energy and therefore more energy has to be taken away to make it stop, gravity as well affects bodies depending on their potential energy relative among each other. Energy is directly related to mass, so conversely you can measure mass by observing the energy ir carries.
And how do you measure energy.I just can't seem to find a way to measure mass by itself without using anything else
Can u measure velocity without using anything else? Or force? this is intersting.
Well I guess since velocity is a derived product of distance and time which can be measured independently.But I don't see mass as a derived quantity of anything
How will u measure distance independently? and time?
With a ruler and a clock
and how does the clock work?
Well what's wrong with using a clock
And I don't think it's a big problem thouh.Time can be measured easily without the use of any other physical quantity
r u certin about it? if somehow all the movment in the univers stops. how will u measure time?
Well,let me think about it.What would you say time would be dependent on?
I'm not saying that your direction of thinking is wrong about mass. But saying that maybe it goes for other quantities
It's quite interesting to think about it.Though I somehow feel that we can measure time independently.Ill have to find out how
ask einstien about it :)
Too bad he's dead
I think so too!
Mass is an intrinsic property of all matter. It is the reason we need to apply a force to move matter, otherwise we needn't have applied any force. You cannot really measure mass without comparing it to something else. Same is true for time and length. But actually these three are the fundamental units, because all other units depend on it.
I agree.But what Im saying is how would you calculate the mass of an object if the only physics you know is "what is mass"
I mean the only way you completely define something is if you know how to measure it right?And mass isn't a derived quantity either
Lately I feel that maybe I'll be able to comunicate with his spirit (at least I hope so) :) About mesurments. From our conversation, I think that all measurments are comparission. As mani jha said In the ruler I compare some distance to another one. In time I compare an event with the tick of the clock, 3, 4 or 10 ticks.. (isn't this somekind of a movment but with a constant speed?) So with mass I can compare two masses, and how strong they attract a third mass Ok, thats an answer maybe, but I think that the questions are more intersting
yes, when something is said to be intrinsical means that it defines itself as it is because it is, nothing else is invloved in defining it this way.
WellI guess we can define something as 1 kg and compare it to something else.But how are you going to compare?
I dont think that mass is defined without length(space) and time. but also time is not defined without mass and space
Why can't we use the F=ma method? Take a mass, give it a push, record the time to cover a certain distance and find the acceleration. Then take another mass, give it the same push, and find its acceleration too. \[m1a1=m2a2\] You can certainly compare the masses. Remember that physicists earlier didn't have a beam balance. You'd have to measure relative masses. Even though you don't have a spring balance, you can certainly tell that both your hands have equal mass. That two blocks which are exactly alike in shape and size have the same mass. Now, suppose I have a small block. Then I get a larger block, and I discover that the larger block can be formed by adding the small block exactly twice. So, I take the small block's mass to be 1 Mani(A new unit that I've defined). Then I can say that the mass of the larger block is 2 Mani. Isn't it? You can also use the F=ma method to get relative masses.
We can't use the f=ma method because we have to measure mass indepently.And the use of beam balance or a spring balance means the use of gravity.And two look alike block means same density blocks which isn't defined because we haven't found how to define mass yet.
f = ma or p = mv2 or e = mc2 or any other equations do not define mass, all equations or equalities are only relations or comparissons were a behaviour is explained, but the very core of what something is never told.
Yeah,that's what i was thinking!
We don't need to use density for that. That would be something you can observe and conclude. You won't need to measure the density of your hands to tell that they have the same mass. If mass was defined by any sort of equation, it wouldn't have been a fundamental quantity. Neither is time or length. These are quantities which you need to measure by comparing it with a standard value. Even time is measured by the time taken for a cesium atom to undergo a certain number of cycles. You can't measure anything independently. Because measurements are artificial methods. They are always relative to some other measurement. We found numbers like this. If there is a single object, the number is one. If there is another, it is two.etc
yes, all of the fundamental units named instrinsic, are only defined as "properties" that describe specific characteristics of the universe which objects obey or follow, the tools the universe uses to make its laws present and work the way they do.
Yet I still believe mass is not one of these fundamental units, nor is energy, temperature, and maybe not even time.
Why? Ultimately mass is the amount of matter in a body. Do you think the amount of matter may depend on some other quantity?
U have a great mind.. Is mass really the amount of matter? I reffer to it as a measure for the amount of inertia, or the measre ofr gravitaional field of a body. By the theory of relativity mass does change with change of speed, or frame of referencce
Yes, mass is actually the amount of matter. It is directly related to inertia and the gravitational field. Mass and inertia are not the same. They're different quantities which are directly related(proportional) to one another. Mass increases, inertia increases. Same with mass and gravitational field. But mass and amount of matter are the same. Even microscopic bodies like electrons have mass.
@Mani Jha You are saying that you don't need the density for that.But what if there was no gravity?Would you still be able to say so?
Mass is independent of gravity. Whether here or in space or on Jupiter, your mass will be same.
Yes so explain how you are going to measure it independently
I told you, no physical quantity can be measured independently. We've to always measure it relative to some other standard. Any measurement is always made relative to a standard. But mass is an independent quantity because it has its own special unit, and all other quantities depend on this quantity. The amount of matter cannot depend on any other physical quantity.
Yeah I think I get it
There is a theory that proposes the property of mass as a result of the vibration within the tiniest particles, vibration of very strange stuff with a very complex shape that does not exist only in the dimensions we know, but covers about 10 different dimensions and according to its shape there is a certain vibration and a certain particle is played.
the mass of the particle is defined by this
well as einstein revealed all properties of an object ARE Relative and mass as well when an object is moving fast relative to me I will measure a higher mass! What do u say about this? than mass does depaned on speed...
There is Einstein again with E = mc2 explaining the mass-energy equivalence and the relativistic mechanics working on moving mass and energy, when an object is moving in a certain direction it gains momentum and kinetic energy, when it travels near the speed of light it wont go faster but still the momentum and kinetic energy can increase unbounded, (this implies that momentum and kinetic energy are not dependent of velocity). Then relativistic mass is defined as this ratio between the momentum and velocity of an object, when the object moves slow the relativistic mass is almost the same as the rest mass, but as it approaches light speed mass increases to infinity as kinetic energy also increases infinitely.
So mass is a relative quantity just like speed, distance and time