Today when I was studying physic for my University enterance exam I have stucked in one topic.

I understood the difference between mass and weight. Mass is the amount of material an object contains and weight is the force applied to that mass due to gravity or other source of potential force(like magnetic feild maybe, not sure)

But when it comes to measurement of mass and weight I just couldnt understand the fact we need at least a little bit gravity to measure mass but then whats the difference between weight and mass now? Without gravity or other force to an object I can't measure weight as well. I am just trying to imagine in very very very low gravity just enough to keep our feets on ground in a scenario like this if I measure the mass will it be same really? Or does that the mass we measure in earth isnt actually mass? just something close to it I just can not quite figure out this with an actual example.

I would be glad if someone explains this to me with an basic example.

  • $\begingroup$ I dont know if there's a modern physics/relativistic/quantum definition for mass, but in classical terms, it is a measure of its inertia (its resistance to acceleration when a force is applied) it should be the same (again, outside a modern physics framework). $\endgroup$
    – user190081
    Oct 2, 2018 at 13:33
  • $\begingroup$ Attach the object to a spring and let it oscillate. Its period will depend on the mass ( as well as on the soring constant) even in zero gravity $\endgroup$
    – b.Lorenz
    Oct 2, 2018 at 14:04

1 Answer 1


We do not need gravity to measure mass, there are lots of scientific experiments where mass can me determined. A particle accelerator is an example where we see motion due to fundamental forces, the motion is affected by mass. Weight always refers to the gravity force, gravity on earth or gravity on the moon, etc.

There are 4 fundamental forces that science studies, and the attraction of masses is due to the gravity force, this is why we see weight on earth. But we can also charge a mass or create a charged particle and use the EM force to study its mass as well.

  • $\begingroup$ It's better not to use "force" in this context with the meaning you are giving to it, i.e. "interaction". OP is a beginner, and in his horizon a force is weight, or elastic reaction of a spring, or friction, or (later) Coulomb force, magnetic force etc. $\endgroup$
    – Elio Fabri
    Oct 2, 2018 at 14:30

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