From Mechanics

\displaystyle F=\text{ 8}00\mathbf{j}\ \text{N},\quad t=\text{ 3}\ \text{s}

\displaystyle \begin{align} & I=Ft \\ & =800\mathbf{j}\times 3 \\ & =2400\mathbf{j} \end{align}

\displaystyle \text{Magnitude of Impulse }=\text{ 24}00\text{ Ns}