Q1. An open-open organ pipe is 67.9 cm long. AN open-closed pipe has an essential frequency equal to the third harmonic of the open-open pipe. How long is the open-closed pipe?
Q2. A smooth board placed at 30 degrees to the horizontal supports a mass of 10 kg that is prevented from slipping by attaching it to a spring lying along the board and fixed at its upper end. Discover the tension in the spring. If spring is removed, what horizontal force would have to be applied to the mass to keep it at rest?