Resposta :
[tex]\large\boxed{\begin{array}{l}\underline{\rm energia\,cin\acute etica}\\\sf k=\dfrac{1}{2}\cdot m\cdot v^2\\\sf v=\sqrt{\dfrac{2k}{m}}\\\\\sf v=\sqrt{\dfrac{2\cdot45}{10}}=\sqrt{\dfrac{90}{10}}\\\\\sf v=\sqrt{9}=3~m/s\end{array}}[/tex]