# Space Gong

1. Apr 23, 2005

### hsutrack

Ok, so here is my dilemma if thats how you spell it. So there is a Gong in space right, and lets say you hit it, does it even vibrate? No sound, of course, but does it still have the vibration necessary to make a sound? And if it does, does it go on indefinitely since and object in motion stays in motion unless acted upon? This is tricky i think, but maybe there is some simple answer. Please! I need peace from this!

2. Apr 23, 2005

### FredGarvin

No. It does not make any sound since there is no medium for the sound waves to propogate.

Yes. It does indeed vibrate.

No. It will not vibrate indefinitely. Internal forces of the gong's material will eventually bring it to a stop.

3. Apr 23, 2005

### jdavel

hsutrack,

To elaborate on FredGarvin's third point, Newton's first law really applies to the motion of an object's center of mass: The motion of the center of mass of an object will not change unless the object is acted on by an outside force. The gong can vibrate without its center of mass moving. On the other hand, if striking the gong gives its center of mass some translational velocity as well as setting it to vibrating, then when the vibrations die out, the gong will still be moving at the original translational velocity.

Newton rules!