# Homework Help: Particle physics problem

1. Jan 18, 2012

### humanist rho

1. The problem statement, all variables and given/known data
A relativistic particle travels a length of 3*10^-3 m before decaying.The decay process of this particle is dominated by.....

(a)Strong interactions
(b)EM interactions
(c)weak interactions
(d)gravitational interactions.

2. Relevant equations

3. The attempt at a solution

Since the question says the particle is relativistic, i took its velocity = c
then,
t = x/v = 10-11
which is the timescale for weak interactions.

But the text says the answer is strong interaction.
Then wheres the mistake?

2. Jan 18, 2012

### vela

Staff Emeritus
Did you take into account time dilation?

3. Jan 25, 2012

### humanist rho

How can i apply time dilation when velocity is not given?

4. Jan 25, 2012

### vela

Staff Emeritus
Good question. Depending on how close to the speed of light the particle travels at, the 10-11 seconds in the lab frame could correspond to an arbitrarily short time interval in the particle's rest frame. I think you need more information to solve the problem.