Well the fancy of the subject "physics" is unexplainable. Understanding of basic terminology gives immense satisfaction.
How many of you could differentiate the three terms "Matter", "Mass" & "Energy" which are essential for beginning understanding of physics?
Let us start explaining things:-
"Mass" is an attribute and not a physical thing. Mass is the attribute "inertia" of a physical object or of what ever is contained in a specified region of space.
"Inertia" is the inherent reluctance to undergo a change in velocity.
If one consults the research documents of decade 1900-10, when Einstein and others developed the equation E=mc2, one finds that for those physicists- the word "Mass" was synonym for "inertia".
"Matter" is tangible stuff; What you can touch and sense with your hands and so a physical thing.Hence all matter has inertia and hence has mass.
"Energy" is the ability to do work. It is an attribute to physical object or of whatever is contained in a specified region of space.
Three general forms for existence of energy are "Kinetic", "potential", "Radiant".
"Kinetic" is the energy associated with motion.
"Potential energy" is the energy that has potential for being converted to kinetic energy.
"Radiant energy" is energy of Electromagnetic waves.
Take a stone and throw into air. The stone which you are able to collect it from ground has got matter as you have touched and sensed it. While moving in air the stone doesn't get blown by wind breeze etc and does possess "inertia". It is moving with a velocity and does has Kinetic energy, at the same time it is at a varying height from ground and hence possess gravitational potential energy.Thus the stone in air has got partly kinetic energy and partly potential energy.
Thus "mass' and "energy" exist as attributes of a physical system, just as do color or shape.
Mass and energy exist in the same fashion and matter exists in different fashion.
Hope this benefits the student community.......Have a nice day
