[tex]Formula\ for\ stress:\\\\
stress=\frac{applied\ force}{cross\ section\ area\ of\ object}\\\\
force=2400N\\
stress=6000\frac{N}{m^2}\\\\
6000=\frac{2400}{cross\ section}\\\\
6000*cross\ section=2400\ \ \ |Divide\ by\ 6000\\\\
\boxed{cross\ section=0,4m^2}[/tex]