Question

A particle has rest energy 1872 MeV and mean lifetime 8.2 × 10−11 s. It is created and decays in a particle track detector. It leaves a track 35 mm long.

(a) What is the

(i) speed of the particle in terms of c?

(ii) momentum of the particle?

(b) How much energy is needed to produce the particle?

(c) Is the particle massless? Justify your answer.

(d) Supported by evidence, give your arguments to the beliefs that the

(i) total energy of the particle is equal to its kinetic energy.

(ii) particle will eventually reach the speed of light if it is continuously accelerated

Answer 1