Why are some insects able to skate on the surface of water while others would sink?&nbsp;<br />Why in some cases, does the water sprinkled on a glass surface collect into drops and in other cases spread like a thin film?&nbsp;
Why does water climb up a thin tube?
Why can you make bubbles with soapy water and not with tap water?
To answer these questions it is important to appreciate and quantify the energy balance at the respective surface or interface.