Sorry! T is for a pendulum. It should be changed to Normal force $\vec{N}$ for your case.
But the equation is the same.
For you case: $\hat{r}$ is the unit vector from (5,0) to (x,y) of the ball.
i.e. unit vector of (x-5,y) or $( \frac{x-5}{\sqrt{(x-t)^2+y^2}}, \frac{y}{\sqrt{(x-t)^2+y^2}})$