[I'm answering in the theoretical context of the standard model,
specifically quantum chromodynamics (QCD). I am not expert in this, so I
don't go into details.]


Sanny wrote:
I read Nucleus has Protons & Nutrons. They join together with Nuclear
Force.

That is only an approximation. The nucleus of an atom with A1 is not
really made up of individual nucleons, because this is a quantum system
and the nucleons don't really have individual identities -- indeed the
number of particles in a given nucleus is not a good quantum number
(i.e. does not have a definite value).

But the success of the nuclear shell model implies that one can
approximate the nucleus as being made up of nucleons....


What is the Equation of Nuclear Force that joins Protons & Nutrons
together.

Far too complicated to post here. QCD has a Lagrangian that would
require many lines of ASCII text. That must be differentiated to obtain
"force", but that is essentially meaningless for such a QUANTUM system.


Just like Gravitational force is ~ 1/(r^2) where r distance between
two masses.

That is a CLASSICAL system. Moreover, that is from Newtonian mechanics
with is merely an approximation to our current best theory of
gravitation, General Relativity. In GR one cannot write down an equation
for "gravitational force" (one can only write down an APPROXIMATION).


Does Nuclear Force which joins protons & nutrons is also proportional
to square of distance between them?

Not really, it's MUCH more complicated than that. For instance, one
cannot even discuss "nuclear force between this proton and that neutron"
because neither of them has a definite identity and "this" does not apply.


What is the distance betwenn twon Protons in a Nucleus?

Again, the question does not really make sense. But the diameter of a
nuclueus is typically a few fm (10^-15 m), depending on the atomic
number A, and scaling roughly as A^0.33.


What is the tecnique to know whats going in between Nucleus and to
measure Nuclear force?

Perform electron-nucleus scattering and analyze the results using a
model of the nucleus and a model of the interactions between electrons
and the nucleus (or its components). This is quite complicated....


Tom Roberts