Question

One end of horizontal string of linear density  kg/m is attached to a small amplitude 60-Hz vibrator. The string passes over a pulley, a distance 1.40 m away and weights are hung from this end.  What mass must be hung from this end of the string to produce (a) one loop, (b) two loops, (c) five loops of a standing wave. Assume that the end of the string with the vibrator is a node, which is nearly true. (d) Why can the amplitude of the standing wave be much greater than the amplitude of the vibrator? (e) Suppose we set the weight so that the 60 - Hz vibrator sets up one loop, as in part a. But now we change the frequency. Which of the following will not produce a standing wave: 90 Hz, 120 Hz, 150 Hz, 180 Hz? Explain why or why not.

Answer 1

Here we apply concept of resonance and standing wave on string. We apply relation between velocity, frequency and wavelength.