• Question: Is toothpaste a solid or liquid because it shares properties of both?

    Asked by ~LUNa.TikK_AtomiC~ to Adrian, Gaia, Jim, Scott, Vicky on 10 Mar 2016. This question was also asked by wllmbrmll.
    • Photo: Scott Lawrie

      Scott Lawrie answered on 10 Mar 2016:

      You are right it has both solid and liquid properties. It truly is a ‘paste’, also known as a ‘Bingham Plastic’. That is a material that sits still without flowing when stationary on your toothbrush (it doesn’t even slowly run off the side over time) but given enough of a squeeze does begin to flow like a liquid.

      There are other weird materials out there. Have a look for ‘Non-Newtonian’ fluids. These do the opposite thing: when you give them a squeeze they become more solid! If you mix it right, you could walk over a swimming pool of custard because it turns solid when you step on it but liquid if you stand still!

    • Photo: Gaia Andreoletti

      Gaia Andreoletti answered on 10 Mar 2016:

      Sorry Scott but then in nature there is a solid state, a liquid state and a “paste” state? You learn something new every day!

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