A vertical tube with a semicircular cross section contains a liquid, as shown in the figure. The contact angle is zero. The ratio of the surface tension force acting on the curved part to the surface tension force on the flat part is

Step-by-step solution

Let the radius of the semicircular cross-section of the tube be R . The surface tension force acting on any part of the wall is given by F = T l , where T is the surface tension of the liquid, l is the length of the line of contact, and is the contact angle. Given that the contact angle = 0^ , we have = 1 . Thus, the force is simply proportional to the length of contact, F = T l . For the curved part, the length of the line of contact is the arc length of the semicircle: l_c = R Therefore, the surface tension force