Assertion : In photon-particle collision the total energy and total momentum are conserved. Reason : The number of photons are conserved in a collision.

In non-elastic collision, both momentum and kinetic energy are conserved.

For a two particle collision, the following quantities are conserved in general-

Prove that the momentum is conserved in collision

Show that total linear momentum is conserved in all collisions.

Which of the following is correct regarding photons? (i) A photon always travels at a speed 3xx10^(8)m//sec in vacuum. (ii) The rest mass of photon is zero. (iii) Let E and p be the energy and linear momentum of a photon and v and lambda be the frequency and wavelength of the same light when it behaves as a wave. Then E=h v =(hc)/(lambda) p=(h v)/(c) =(h)/(lambda) =(E)/(c) (iv) A photon may collide with a meterial particle. The total energy and the total momentum remain conserved in such a collision. The photon may get absorbed and / or a new photon may be emitted. Thus, the number of photons may not be consverved.

Assertion : In elastic collision, kinetic energy is conserved. Reason : Energy is always conserved.

Assertion : In elastic collision, kinetic energy is conserved. Reason : Energy is always conserved.

Momentum is conserved in a two-body collision only if