# Is it possible to calculate the rest mass of a pion given only its E ?

1. Mar 6, 2014

### rwooduk

The TOTAL energy of a pion is given, no other information is given so we don't know how fast it is moving, is it possible to calculate its mass? I'm assuming it's relativistic and we need GAMMA (the lorentz factor)

Also if E is it's total energy what would it's kinetic energy be? wouldnt its kinetic energy be its total energy?

Thanks in advance for any help on this, ive been going round and round in circles.

2. Mar 6, 2014

### BvU

E = mc2 should help you find the mass when E is given
Here m is not the rest mass, because that requires $\gamma$ for $m = \gamma m_0$.
So if are they asking for the rest mass the answer is no.
But you ask whether it's possible to calculate the mass (period).

3. Mar 6, 2014

### rwooduk

Thanks very much for the reply!