6.5 Suppose that the C-shaped wire frame in Figure 6.1 is rotated clockwise by 90°, so that the sliding wire would fall down if it were free to do so. The sliding wire has a length of 3.5 cm and a mass of 0.20 g. There is no friction between the sliding wire and the vertical sides of the C-shaped wire. If the sliding wire is in equilibrium, what is the surface tension of the film? I