You’re probably wondering why there are so many tangent lines on these diagrams, these are tangential forces. Tangential force is the direction that is in a tangential (hence the word TANGENT in tangential) direction to the circular path. Meaning it shows the direction the object is always going to go in at that point. Now, a softball pitcher is an example of circular motion because when she begins to wind up for her pitch, the ball is going along the circumference of which her arm is directing it to. Her arm becomes the centripetal force while her shoulder is the center because that is what is causing the rotation of the ball and arm. Once the pitcher releases the ball, it is also releasing the centripetal force (causing the ball to go along the circular path) and allows the ball to contain the same velocity and acceleration it had while she was winding up. That is why the pitch remains in the tangential direction (a straight line) once it is released.