A liquid is contained in a vertical tube of semicircular cross-section (figure). The contact angle is zero. The forces of surface tension on the curved part and on the flat part are in ratio:
1. \(1:1\)
2. \(1:2\)
3. \(\pi:2\)
4. \(2: \pi\)
Air is pushed carefully into a soap bubble of radius \(r\) to double its radius. If the surface tension of the soap solution is \(T,\) then work done in the process is:
1. | \(12\pi r^2T\) | 2. | \(24\pi r^2T\) |
3. | \(4\pi r^2T\) | 4. | \(8\pi r^2T\) |