An electron has a total energy of 2MeV.Calculate the effective mass of the electron in Kg and its speed .Assume rest mass of electron 0.511MeV

Question

$\begin{array}{1 1}(a)\;23.6\times 10^{-31}Kg,3.9\times 10^{10}cm/s\\(b)\;35.6\times 10^{-31}Kg,2.9\times 10^{10}cm/s\\(c)\;21.6\times 10^{-31}Kg,1.9\times 10^{10}cm/s\\(d)\;23.6\times 10^{-19}Kg,2.9\times 10^{5}cm/s\end{array}$