# Special Relativity Problem.

1. Jun 5, 2010

### QuantumJG

1. The problem statement, all variables and given/known data

A particle has a rest mass of m0 and a half life of t0. An observer measures the half life of the particle, which has a total energy of E and a momentum of p.

Find an algebraic expression for the half life the observer measures for the particles, using only the symbols defined above.

I really don't know how to start this problem!

2. Jun 6, 2010

### tiny-tim

Hi QuantumJG! :smile

With questions like this, be logical

start by writing out all the relevant equations you know (in this case, including the decay-rate equation) …

what do you have?

3. Jun 6, 2010

### QuantumJG

Really all that I have is:

E^2 = (pc)^2 + (mc^2)^2

t = γt_0

4. Jun 6, 2010

### eXorikos

And the equations for the decay?

5. Jun 7, 2010

### diffusion

Hi Joel. :)

This problem becomes very simple when you recognize that

$\gamma = \frac{E_{total}}{E_{rest}}$