Question

The figure shows a golf ball passing through a windmill at a miniature golf course. The windmill has 8 blades and rotates at an angular speed of 2.02 rad/s. The opening between successive blades is equal to the width of a blade. A golf ball of diameter 3.27 x 10-2 m is just passing by one of the rotating blades. What must be the minimum speed of the ball so that it will not be hit by the next blade?

I understand the how this works logically just not how to arrive at the answer. thanks