# Special Relativity - Energy Problems.

A particle of mass 3.5 MeV/c2 and kinetic energy 4.5 MeV collides with a stationary particle of mass 0.5 MeV/c2 . After the collision, the particles stick together.

(part 1 of 5)

Find the total energy of the first particle before the collision. Answer in units of MeV.

(part 2 of 5)

Find the speed of the first particle before the collision. Answer in units of c.

(part 3 of 5)

Find the initial total momentum of the system. Answer in units of MeV/c.

(part 4 of 5)

Find the mass of the system after the collision. Answer in units of MeV/c2 .

(part 5 of 5)

Find the total kinetic energy after the collision. Answer in units of MeV.

https://brainmass.com/physics/energy/special-relativity-energy-problems-145386

#### Solution Preview

Please see the attached file.

The total energy of a particle is the sum of its rest mass and its kinetic energy:

In our case the total energy of the first particle is:

However, the total energy is also given by:

Hence the speed of the particle (in units of c) before the collision is:

The initial speed of the first particle is:

The relation between momentum and energy ...

#### Solution Summary

Special relativity and total energy of particles before, during and after collision are given.