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Q & A: Dripping Water

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Most recent answer: 10/22/2007
Q:
Drops of water falling from a dripping faucet As they fall do they 1. get closer together 2. get farther appart 3. remain a fixed distance 4. Unable to determine
- Mike
Allan Hancock College, Santa Maria, CA
A:
Hey, I bet you could answer this if you tried.

Each drop accelerates as it falls. So the last drop to fall is always falling slower than the one ahead of it. So the distance between them is increasing.

After they fall for a while, air friction will reduce the acceleration, so the distance won’t change so much, but they’ll still get farther apart at some rate.

You can usually get water to form a thin stream as it exits the faucet. The stream will be thicker near the top than it is farther down (the cross-sectional area of the stream times the speed of the water is the same everywhere in the stream, and the speed of water that has fallen a greater distance is higher than the speed of water that just came out of the faucet). At some point the stream will get so thin that the total energy in the surface tension of the water can be reduced by breaking the stream into droplets (spheres are the shapes that minimize surface area). Then the droplets will get farter apart from each other as they continue to fall.

Mike W. and Tom J.

(published on 10/22/2007)

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