Resposta :
[tex]\large\boxed{\begin{array}{l}\sf E_c=\dfrac{1}{2}\cdot m\cdot v^2\longrightarrow v=\sqrt{\dfrac{2\cdot E_c}{m}}\\\\\sf v=\sqrt{\dfrac{2\cdot1690}{20}}=\sqrt{\dfrac{3380}{20}}\\\\\sf v=\sqrt{169}=13\,m/s\end{array}}[/tex]
[tex]\large\boxed{\begin{array}{l}\sf E_c=\dfrac{1}{2}\cdot m\cdot v^2\longrightarrow v=\sqrt{\dfrac{2\cdot E_c}{m}}\\\\\sf v=\sqrt{\dfrac{2\cdot1690}{20}}=\sqrt{\dfrac{3380}{20}}\\\\\sf v=\sqrt{169}=13\,m/s\end{array}}[/tex]