Hello!
[tex]\large\boxed{F_{c} = 8N}[/tex]
Use the equation for Centripetal force to solve:
[tex]F_{c} = \frac{mv^{2}}{r}[/tex]
Plug in the given mass, velocity and radius to solve:
[tex]F_{c} = \frac{2*4^{2}}{4}\\\\F_{c} = \frac{32}{4}\\\\F_{c} = 8 N[/tex]