Answer:
[tex]F_{cp}=88.43N[/tex]
Explanation:
The equation for centripetal force is given by Newton's 2nd Law:
[tex]F_{cp}=ma_{cp}[/tex]
The equation for centripetal acceleration is [tex]a_{cp}=r\omega^2[/tex]
If the object makes one revolution (an angle of [tex]2\pi rad[/tex]) every 5 seconds it means that its angular velocity is [tex]\omega=\frac{2\pi rad}{5s}[/tex].
Putting all together, and for our values:
[tex]F_{cp}=ma_{cp}=mr\omega^2=(8kg)(7m)(\frac{2\pi rad}{5s})^2=88.43N[/tex]