Posted by: Dave P (cdpaetkau@telus.net) on Mon Jun 26 20:11:09 2006

> >>> I don't hear much talk here about the importance of momentum in the swing. Batspeed itself is good, but a slower batspeed with greater momentum can hit the ball harder and this is the real reason the swing should be rotational and your arms should not disconnect from your body.
>
> Every swing goes from stop - max speed - stop. In between stop - max speed, the bat is speeding up. In between max speed - stop, the bat is slowing down. Forces acting on the bat between stop - max speed are in the same direction the bat in traveling while forces acting on the bat between max speed - stop are in the opposite direction.
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> It is very important that contact is made at a point closest to max speed, but between stop - max speed so that the forces are behind the bat and give the most momentum and greater force on the ball. If contact is made just after max-speed and in between max speed - stop, the batspeed may be very close to when contact was made just before max speed, but momentum will be much less and the force acting on the ball will also be much less.
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> If that concept doesn't make sense to you,, imagine getting hit by a baseball traveling 100 MPH. Now imagine getting hit by a train traveling 50MPH. Which one will make you fly further?
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> ##
>
> Just a little further info. Momentum = Mass x Velocity. for solid moving objects, mass does not change. In a baseball swing, if your arms rotate properly with your body, the mass is your entire body. If the arms disconnect and do not rotate with your body, the mass gets reduced to your arms only. So, you can see that two 80 MPH swings are not the same if the largest possible mass is not obtained through proper mechanics. <<<
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> Hi Tony
>
> For the most part, I agree with your post. However, I must disagree when you say, “Batspeed itself is good, but a slower batspeed with greater momentum can hit the ball harder and this is the real reason the swing should be rotational and your arms should not disconnect from your body.”
>
> The only momentum that determines how hard a ball is hit is the mass of the bat. The mass (or momentum) of the limbs and torso is not a factor. Neither is the grip or torque applied at the handle during the bat/ball collision.
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> A bat attaining 70 mph swung on a rope will hit the ball just as hard as a 70 mph bat welded to a 200 lb. flywheel. It is the mass, composition of the bat and its velocity at contact that determines how hard the ball is struck.
>
> Jack Mankin

Hi Jack

I do not disagree with you but on the statement that

"The only momentum that determines how hard a ball is hit is the mass of the bat. The mass (or momentum) of the limbs and torso is not a factor. Neither is the grip or torque applied at the handle during the bat/ball collision."

is incorrect in complete terms. At contact the positioning of the hands (grip and position), elbows(mainly the back elbow) and arms makes a great difference to the power exerted on the ball due to the following reason. Every collision that occurs when two objects are moving in different directions impart forces on each other that affect that objects movement and thus affect the resultant change of direction and velocity on the formentioned objects.

Example when you bunt the ball the firmer you hold the bat the further the bunt goes and the more you absorb the pitch the shorter the ball goes.

When you swing the bat and the wrists are in the incorrect position (rolling over) the ball impacts on the bat more due to the wrists collapsing during the contact and the direction of the bat starting to go upward at contact. If your back elbow is not tight to the body the elbow and wrists absorbs more of the balls energy (though less then the wrists being in the wrong postion).

Another example is throw a ball against a brick wall and the ball comes back quickly because most of the energy is transfered back into the ball as the wall does not move. Throw a ball against a gyproc wall and the ball does not come back a quickly as the wall asorbs more of the energy as it flexs as it is hit with the ball (the back elbow away fromt he body). Throw the same ball against a foam wall and the ball rolls back slowly as the foam absorbs most of the energy (the wrist rollover).

I hope this all makes sense but like I said a blanket statement doew not work here with the f=ma formula.

Dave P