Each decay of a certain nuclide releases of energy

PHYSICS · Subjective · A Level · Physics · Nuclear physics · Nuclear physics

Problem

Each

\beta^{-}

decay of a certain nuclide releases

3.2\,\text{MeV}

of energy. A sample initially contains

2.0\times10^{18}

nuclei of this nuclide and has a decay constant of

0.040\,\text{s}^{-1}

. Calculate the total energy liberated by the sample in the first 15 s. Express your answer in joule.