>>13822116all human knowledge is circular reasoning. if you don't put postulates and axioms and definitions you can't do anything. newton decided work means change of velocity of a mass over a distance so that's the definition we will use forever and there is nothing you can do about it but cry.
work is dot product of displacement and force vectors. more generally it's change in a system but not all change is work. energy is the ability to do work but there are different kinds of energies so definition varies a bit. to make things more confusing, something might have energy but it might not be able to do work. yeah also energy is scalar (i.e. has no direction)
