Determine the rest mass of the ${\Lambda ^0}$ particle.

Determine, using your answer to (a), the initial speed of the ${\Lambda ^0}$ particle.

$\Lambda$ momentum = 900

E_proton = «$\sqrt {p{c^2} + {{\left( {m{c^2}} \right)}^2}}  = \sqrt {{{630}^2} + {{938}^2}}  =$» 1130 «MeV»

E_pion = «$\sqrt {{{270}^2} + {{140}^2}}  =$» 304 «MeV»

so rest mass of $\Lambda$ = «$\sqrt {{{\left( {1130 + 304} \right)}^2} - {{900}^2}}  =$» 1116 «MeV c^–2»

«E = $\gamma$ mc² so» $\gamma$ = « $\frac{{1434}}{{1116}}$ =» 1.28

to give 0.64c