You notice that the ping-pong ball sinks into the water as it falls.
Explain.
2007-12-18 07:21:49 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Physics
During free fall, it and the water become weightless and the surface tension of the water will pull it in.
2007-12-18 07:25:05 · answer #1 · answered by DaveNCUSA 7 · 6⤊ 0⤋
The buoyance force is based on the net aceleration of the water and the ping-pong ball. Because of air resistance, there will always be some net force of gravity on the ball and the water and it will be proportionately the same as before the fall, so the fall will not cause the ball to sink.
As to the surface tension, mentioned above, that would cause a slight sinking because it is constant and it will have a relatively stronger effect compared to the buoyancy, at least until the cup reaches terminal velocity. (If the surface of the pingpong ball is hydrophobic, the ball will go up instead of down).
But one last thought: Bernouli's equation. This might set up an eddy in the wake of the cup which would push the ping-pong ball down into the water. But just as likely, these air flows will knock the ping-pong ball off of the water surface and cause it to float freely in the air.
But, I really think you need to film this. Just get your cup of water, ping pong ball and video camera and jump off a nearby building. lol
2007-12-18 08:01:49 · answer #2 · answered by Frst Grade Rocks! Ω 7 · 3⤊ 1⤋
The acceleration of the object causes it to move down, just like if you were to take a ping pong ball and slam it into the water, the ping ping ball would go to the bottom of the container but eventually come back up because it was less dense then the water.
2007-12-18 07:27:18 · answer #3 · answered by the s0urce 3 · 0⤊ 2⤋
The cup's downward velocity is dampened by resistance between the cup and the air. The ping pong ball has an entirely different frame of reference to the cup. It is effectively falling through water. Presumably, because it is wetted, the resistance it experiences from the water is less than that experienced by the cup from the air so it falls faster thereby sinking into the water.
2007-12-18 07:26:58 · answer #4 · answered by Anonymous · 0⤊ 2⤋
the upward buoyancy force, normally keeping the ball afloat against gravity, is now partially cancelled by the downward force of the accelerating ball. it would thus find a new equilibrium position, lower than before (i.e. partially submersed).
2007-12-18 07:33:15 · answer #5 · answered by clavdivs 4 · 0⤊ 2⤋
Impact power?
2007-12-18 07:25:22 · answer #6 · answered by Anonymous · 0⤊ 2⤋
it shudnt bounce back out
2007-12-18 07:25:23 · answer #7 · answered by Bugzy M 2 · 0⤊ 1⤋
I'm up on the roof.........hold on for the answer!
2007-12-18 08:38:29 · answer #8 · answered by kisser 4 · 6⤊ 1⤋