Axis of Supension Centers of Oscillation and Percussion
المؤلف:
GEORGE A. HOADLEY
المصدر:
ESSENTIALS OF PHYSICS
الجزء والصفحة:
p-93
2025-11-05
33
Demonstration. - Bore a quarter-inch hole through the handle of a baseball bat near the end. Drive in a piece of dowel pin for an axis, and suspend it as in A (Fig. 1). Set it vibrating, and determine its length as a pendulum by comparison with the simple pendulum D. Mark off this length BC from the lower side of the pin B, and put a second pin through, with its upper side at C. Invert the bat and vibrate from C, and it will be found to vibrate in the same time as before.
FIG.1
The axis at B, in the left half of Fig. 1, is the axis of suspension. The point Cis the center of oscillation, and the demonstration shows the important fact that the axis of suspersion and center of oscillation are interchangeable.
The point C is also the center of percussion, and a ball striking the bat at this point will receive the full effect of the blow. The position of the hands in holding the bat and the swing given to it will change the position of the center of percussion slightly. If the ball is struck too far from this point, the effect will be to sting the hands.
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