Problem #0172 Mechanics Sub-menu Problem #0174 Mechanics Main Menu Home Page

173.

Problem 21.53 (RHK)

A particle of mass m travelling at a relativistic speed makes a completely inelastic collision with an identical particle that is initially at rest. We have to find (a) the speed of the resulting single particle and (b) its mass. We will express our answers in terms of the Lorentz factor of the incident particle.

Solution:             Click For PDF Version

(a)

Let the mass of the particles be m.

Let the speed of the incident particle be v.

The Lorentz factor is defined as .

We note

Initial momentum of the two particles one of which is at rest is

The initial total energy of the two particle system is

Let the mass of the two-particle system after the inelastic collision be M and its speed be V.

The momentum of the system after the inelastic collision will be

The energy of the system after the inelastic collision will be

From conservation of energy, we have

From conservation of momentum, we have

(b)

And,