• Question: why do boats float???

    Asked by whdavandbeat to Anil, Blanka, Cees, Emma, Mike on 3 Jul 2012.
    • Photo: Emma Trantham

      Emma Trantham answered on 3 Jul 2012:


      Good question 🙂

      Ok just moving away from boats for just a minute.

      Have you ever noticed that when you get into a bath/paddling pool etc. the water level rises? In fact if it is really full then the water can overflow! Well this is because you are displacing the water (basically moving it out the way). When you do this you are applying force to the water (that’s what makes it move out of the way) and the water is applying force to you as it tries to get back to where it was before (although you don’t really notice this force).

      Back to boats…

      Boats float when the displace (move out the way) an amount of water that weighs at least as much as they do. This is because the force of the boat on the water is the same as the force of the water on the boat. If they are the wrong shape and so don’t displace enough water the force of the boat will be more than the force of the water and so they will sink.

      Does that make sense?

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