How to turn a leaf into a boat

Turning a leaf into a boat using liquid soap




  • leaf;
  • cot­ton swab;
  • liq­uid soap;
  • glass dish;
  • wa­ter.

Step-by-step in­struc­tions

Ap­ply some liq­uid soap to the tip of the leaf with a cot­ton swab. Toss the leaf into a dish filled with wa­ter. Note that it sails like a boat!

Process de­scrip­tion

At the bor­der be­tween the boat and the wa­ter’s sur­face, the wa­ter is ac­tive­ly “pulling” the boat to it­self. This force “pulls” the boat in all di­rec­tions equal­ly, and there­fore the boat re­mains sta­tion­ary. This force di­rect­ly de­pends on sur­face ten­sion. Soap con­tains sur­fac­tants, which re­duce the sur­face ten­sion of the wa­ter. This weak­ens the soapy wa­ter’s “grip” on the boat sig­nif­i­cant­ly. It would seem that soap push­es the boat for­ward; in fact, the op­po­site is true! The undi­lut­ed wa­ter pulls the boat hard­er than the soapy wa­ter, draw­ing the boat away from the soap film.