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At sea level, in a vacuum chamber (devoid of air but not of the effects of gravity) with a height 9.75 meters (32 feet), a bowling ball weighing 7.26 kg (16 pounds) and a feather weighing 0.0082 grams (0.00029 ounces) are dropped simultaneously.

1) How soon after the bowling ball hits the ground will the feather hit the ground?

2) Which one makes the loudest sound on impact with the ground?

3) Will the bowling ball vibrate for longer if we introduce air into the chamber?

Here's the video of this experiment.

... and here's the whole story.

1) They hit at the same time.

2) There is no sound because there is no air.

3) The air will absorb some of the vibration energy, so the ball will vibrate for a shorter period of time.

The bowling ball and the feather strike the bottom simultaneously if and only if the bottom of the feather were even with the bottom of the bowling ball at the release time.

There is no sound in the chamber, unless you count the sound of the impact of the bowling ball propagating through the solid walls of the chamber.  I think the bowling ball will vibrate longer in a vacuum, since there is nothing other than the ball

to dampen its vibrations (other than the bottom wall of the chamber). - James S.