Hi! I'm revising for my graduation exams and I unfortunately got stuck thinking about surface tension, esp about the example of a needle lying on water. When you look on this drawing from Wikipedia, only two surface tension forces are shown. These two forces are tangent lines at the points where the needle and water surface get separated. But what about the other points? Are there any surface tension forces at the red points in the next drawing? Or do surface forces act (exist) only along "seperation" lines? Thanks!