Is my interpretation of mass accurate?

Question

Mass is the inertial tendency of an object. Objects with greater mass speed up and slow down less quickly than objects with lower mass. Something that has no mass, like a photon, could accelerate to the speed of light in an instance.

Is that correct? Anything you could add to that or point out would be most appreciative.

Answer 1

Yes, that is all true. Mass has inertia and inertia is affected by the amount of mass. Objects with greater mass don't necessarily speed up and slow done slower, but it requires more force to do so. Mass is basically the amount of matter in an object. That is the general definition of mass and the one that the use in the scientific community (I think- might be wrong).

Be sure not to confuse weight with mass- weight is a measure of force and mass is the amount of matter. My science teacher taught me both definitions, but the latter is more commonly  used.

Answer 2

the inertial definition of mass is one interpretation. Eistein gave us mass as the source of warping of space time. But that's gravity. in electrodynamics we use the intertial mass definition.

Couple of changes - It takes more force to give a more massive object the same acceleration one gives a less massive object. This is the basic defenition of interia - a resistance to change in motion; it seem heavier masses require more force to move the same way by a factor M the mass of the object, so M is called the inertial mass.

Something that has zero rest-mass ALWAYS travels at the speed of light. There is no acceleration. It just that when it interactes with a molecules it gets bounced around and the effective distance is covers in smaller than in pure vaccuum, so the average speed is less than of light in vaccuum.

hope that helps