Quote by bigerst
I'm just uncertain (haha), what IS newton's Second law exactly?
F=ma, or F=dp/dt, aren't these defining equations for F itself? what is a force? what would you mean a "force" acts on a object, would it be equally probable to define say, d^3Q/dt^3 = m dx^3/dt^3?
does newton's second law have anything to do with the fact that coulomb, gravity etc can be expressed as a second order differential equation? is it a definition, or an accident?

Newton's laws were written after some experiments. force is actually a word for 'interaction'.
Newton observed that a body could move with uniform velocity without any support or interaction form another object in a particular direction. So any interaction would cause a change in velocity , thus F=m*(dv/dt). (forces are abstract)
Forces can't be seen, but the changes due to it can't be clearly seen. The object's changes help calculate forces.
How can the physical laws be an accident ? birth of human s may be an accident, but physical laws,No. Coulumb's law and Theory of gravitation defines force caused due to charge and mass interactions. Well it's interaction, but without any contact. So they are forces irrespective of their birth.