Suppose you are in a boat on a pond and you are holding a small 10 lb weight. You drop the weight into the water. Does the water level rise, stay the same, or lower?


1 Answer 1


When the weight is in the water

it displaces the same volume of water as itself.

When it is in the boat

it causes the boat to display a volume of water with the same mass as itself.


the weight is presumably denser than water,

when you drop it in

it will displace less water and the level of water in the pond will therefore sink.

  • $\begingroup$ Whoops, sorry for being stupid. I'm on mobile and couldn't find the search function easily. Clearly I'm blind, and that's no excuse anyway. $\endgroup$
    – Quintec
    Commented Jul 18, 2017 at 17:55
  • $\begingroup$ No apology needed -- oversights are easy :-). $\endgroup$
    – Gareth McCaughan
    Commented Jul 18, 2017 at 20:12

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