Hi Howard and Sammy
Sammy.....I knew exactly what you were talking about. I totally agree with you about using new technologies. I just hate NASCAR! It was nothing against your post.
Howard.....thanks for the links.
I must admit that I made a huge error in my first post. I knew what I meant, but my thoughts did not travel to my typing. Of course a centripetal force requirement pertains to Newton's "Laws Of Motion". I meant to say that since it is a kinematic force requirement you cannot use f=ma to calculate a trajectory, which was actually cut and pasted by you from Wikipedia so thank you for correcting my statement.
So what does "centripetal force requirement" mean? It simply means that centriptel force is a force requirement necessary for a curved trajectory to be possible. It is nothing more than an implied force. Another force is doing the work, and I believe that force is centrifugal force.
http://www.physicsnews1.com/question_5.html
There is a great debate amongst physicists about whether centrifugal force is ficticous or real. I believe it is real because it can be proven. The physicists that deny centrifugal force is a real force are the ones that do not want to sway from what they were taught. They're afraid the walls would crumble around them. They would rather call the rotational outward fleeing force with magnitude and direction "torque". It's amazing that torque can be real but centrifugal force must remain fictitious.
The other link you provided to me had a section called "How To Swing A Bat". The author calculates centripetal force as if it were a kinetic force. Also, he is observing it from an external reference point instead of putting himself in the middle of the rotational reference frame. He also thinks that a batter swings with his or her arms and a little wrist action, totally ignoring the larger muscles in the trunk and legs used in swinging a bat correctly. Basically, his calculations and observations provided very little useful information in my opinion other than the push/pull forces on the bat handle, which of course are helping the bat to rotate. The author is basically denying the existence of centrifugal force due to what he was taught in my opinion.
The end result of a hit is a ball following a vector, ie. the ball is hit with magnitude and direction. This vector is the result of a net force acting on the ball. According to Dynamics, this net force must be kinetic so it cannot be centripetal force.
Your opinions may vary.....Physics is an inexact science.
Len