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A Sounding Body isa Vibrating Body

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-194

2025-11-16

665

Demonstrations. Hold a large jar, like the receiver of an air pump, horizontally by the knob, and draw a bow across the edge, or strike it lightly with a cork hammer. Is it a sounding body? Place a few carpet tacks inside the jar near the edge. Repeat the experiment. Is the jar in vibration?

Bore a hole in the top of a table and firmly set into it the handle of a tuning fork. Make a cork hammer by thrusting one end of a knitting needle through a large cork. Tie a shoe button to the end of a fine silk thread. Strike one prong of the fork with the hammer, and hold the button on the side of the fork near the top. Do its movements prove that the fork is a vibrating body? Why does not the button rebound to the same distance every time? Gradually lower it along the side. What is the effect? Hold the button between the prongs and observe.

Both these experiments prove that a sounding body is in vibration. An interesting way to show the vibration of a tuning fork is to set it in motion, and then bring it in contact with the surface of water upon which lycopodium powder has been scattered. The rapid blows of the prong will give rise to a beautiful set of waves.