Interesting Question of the Day – 16 January 2017

If you were standing on boat holding a rock, then threw the rock in the lake and let it sink, would the water level of the lake go up, go down, or would it stay at the same level?  (We’re assuming this is a closed system.  Nothing is flowing into or out of the lake.)

The first new player to comment on the website with the correct answer wins a free drink at their next iQ Trivia show.

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4 comments on “Interesting Question of the Day – 16 January 2017
  1. Drew says:

    Water level drops. In the boat you have displaced the rocks wieght in water throw the rock in you only displace the rocks volume.
    Rock is 4 times denser than water.

    So yeah it drops.

    • iqtrivia says:

      It does drop.

      If you imagine a small but extremely heavy rock, it’s going to press the boat down in the water quite a bit which raises the water level, but when you toss it, the boat goes up and the water goes down, and when it sinks it goes from displacing its mass of water to displacing only its volume.

  2. Jessie Richardson says:

    The water level would stay the same