Discovering the Mystery Behind the Direction of Water Swirl in Your Sink

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Discussion Overview

The discussion revolves around the factors influencing the direction of water swirl in sinks, exploring the potential role of the Earth's rotation and other disturbances. Participants express curiosity about the underlying reasons for the observed phenomena.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions the commonly held belief that the direction of water swirl is determined by the Earth's hemisphere and seeks alternative explanations.
  • Another participant acknowledges the theoretical effect of Earth's rotation but suggests that this effect is often overshadowed by initial conditions, such as pre-existing water rotation.
  • A participant prompts others to share personal observations regarding the swirl direction in their own sinks.
  • One participant humorously notes an unsuccessful attempt to observe the swirl due to a blocked drain.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the primary cause of water swirl direction, indicating multiple competing views and unresolved questions.

Contextual Notes

The discussion highlights the influence of initial conditions on water swirl, but does not resolve the implications of Earth's rotation or the extent to which it may affect the outcome.

tomlib
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I have a trivial question. What causes the direction in which the water in the spout turns? They say it's according to the Earth's hemisphere, but I don't really believe it and I'm looking for other reasons. Finally, even this reason would have to have some explanation.
 
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So, there is a theoretical effect due to the rotation of the earth. However, usually that is swamped by other disturbances like the initial state. So if there is only the slightest rotation already in the water before you start draining that will easily decide the rotational direction. Veritasium and Smarter Every Day did a video on this:

 
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Did you fill and empty the sinks in your house to see which way they swirl? What did you learn?
 
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That I blocked the drain with a match.
 
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