Which of the following is not a derived force ???1) Tension in a String.......2) van der waal forces...........3) Nuclear force between proton- proton..................4) Electrostatic force between proton -proton.......( I am confused between 3) and 4) !!! kindly answer with explanation !!! )

sir , m having more doubts !!! fundamental force is ELECTROMAGnetic force na?? n it is quite diff from electrstatic force !!???

i mean sir , electrostatic force is a special case of electromagnetic force??? isn't it??? so can we include it too in fundamental forces??? pls reply fast

Yes electromagnetic force is the fundamental force experienced by moving charges and electrostatic is when charges are at rest. But both are fundamental forces.

Quantum mechanics describes fundmental particles as carriers of force. These fundamental particles are called gauge bosons. Gluons are carriers of strong interaction. W and Z bosons are carriers of weak interaction. Similarly photon is the gauge boson responsible for electromagnetic force(it is called electrostatic force in static condition, special case you can say). Graviton is the gauge boson for graviation. Bosons are particles having either 0 spin or integral number spin.

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Out of six flavours of quarks, two are stable(up and down quark) which make up stable matter (protons and neutrons). Proton is just a group of three quarks, when quarks of one proton and quarks of other proton or neutron interact via gluons, the protons/neutrons feel the residual attaction called nuclear force. The strong interaction between the quarks is a fundamental force.

Nuclear force is only a residual effect of strong interaction. It's parameters and equations are not known yet. It is not a central force, nor does it obey inverse square law. It does not involve weak interaction. The nuclear forces are very weak compared to direct gluon forces ("color forces" or strong forces) inside nucleons, and the nuclear forces extend only over a few nuclear diameters, falling exponentially with distance. Nevertheless, they are strong enough to bind neutrons and protons over short distances, and overcome the electrical repulsion between protons in the nucleus.

Earlier strong interaction was referred to the inter-nucleon force, but now after the verification of the quark model the nuclear force is called the residual strong force, in contrast to the fundamental strong interactions between quarks which is now understood in light of quantum chromodynamics. Quantum chromodynamics (QCD) is a theory of the strong interaction (color force).

checkout this animation to see how strong interaction works.

http://upload.wikimedia.org /wikipedia/commons/ 3/35/Nuclear_Force_anim _smaller.gif

the small colored circles are gluons, they attach with one quark and forms a pi-meson, which is exchanged between the nucleons. This exchange is called strong interaction.

Whereas the first three fundamental forces(graviation/ electromagnetism/ strong interaction) act through attraction/repulsion mechanisms, the weak force is responsible for transmutations from proton to neutron by changing the flavour of quark and causing radioactive decay. The interactions can be understood using Feynmann diagrams. This will not be taught to you in graduation courses. You may study it in higher physics in post graduation.

aah...quite difficult to understand..anyways..thanks sir :)