Posted by: Chuck (Chuck10112@gmail.com) on Sun Aug 17 19:35:22 2008

> The rearend of an automobile that is going 70mph and then hits a telephone pole with its right headlight doesn't come around does it?
>
> Where was the trust?
>
> Did that headlight pull it around?

This is a good analogy I should have used it in my explanation.

Actually the rearend of an automobile going 70mph that hits a telephone pole with its right headlight WILL come around. If the car and telephone pole are rigid enough (i.e. don't absorb the energy of the collision) then the energy of the collsion will be redirected. If the collision were straight on (assuming the pole is immovable) the car would simply go backwards. But since the collsion is off center with the right headlight hitting the pole, the rearend of the car will swing around to left side rotating about the point where the car and pole collided.

Now obviously in reality the car and/or the pole would absorb practically all of the energy through deformation (i.e. car or pole being severely dented or pole simply being knocked over) so you wouldn't see the rear end of the car swing around. Remember that law you learned in your high school physics class? The law of conservation of energy... energy doesn't disappear it's either absorbed/dissapated (like with a real word car crash) or it's redirected (like with my example in the first paragraph).

To answer your other two questions the thrust comes from the car actually moving at 70mph and the headlight doesn't "pull" the car around but it causes the moving car to undergo rotation since the collision was off center, this rotation causes the rear end of the car to swing to the left. The headlight redirects the energy of the 70mph car, it doesn't magically pull it around.

I don't know if you guys have ever taken a physics class, but you should know that there is not such thing as a rotational force. All forces are linear. If you change the directtion of a force swiftly enough it will appear as though the force is "rotational" but really it's just a cause of multiple linear forces.

The hips are thrust sideways towards the pitcher like the car moving at 70mph,

The front leg acts as the headlight, redirecting the energy created by the moving hip, causing the body to rotate about the front side (NOT THE SPINE) which pulls the backside through. This is why you sometimes see MLB players with their back foot completely off of the ground at contact. This would NEVER happen if the axis of rotation was the spine no matter how hard you swung the bat.