Waves

A hollow pipe of length \(0.8 \mathrm{~m}\) is closed at one end. At its open end, a \(0.5 \mathrm{~m}\) long uniform string is vibrating in its second harmonic and it resonates with the fundamental frequency of pipe. If the tension in the string is \(50 \mathrm{~N}\) and speed of sound in air is \(320 \mathrm{~m} / \mathrm{s}\), the mass of the string is