Question

6. A cord of ρ = 30 g/m is tightly tied between two strong posts a distance 3.0 m apart, so that it is under a tension of 100 N.
The cord is plucked so that resonant standing waves are set up.
(a) Find the three longest wavelengths that are allowed in the cord.
(b) Find the corresponding frequencies.
(c) The tension is now adjusted so that the new fundamental frequency corresponds to that of the second overtone in
part (b);find the new tension.

7. A brass rod is firmly clamped at the center and when tapped at one end resonates longitudinally with a fundamental of
2000 Hz.
(a) What characterizes the resonant standing waves at the rod ends?
(b) What next higher frequency would you expect to be resonating under the conditions described, and why?

Answer 1