A student investigates stationary waves with an elastic cord of circular cross-section attached to a load, as shown in Fig. 1.1. [Figure 1.1] When the frequency of the vibrator is f, the cord vibrates with the stationary wave pattern shown. The student investigates how f varies with the cross-sectional area A of the cord. It is suggested that the relationship between f and A is f = 1 / (2L√(M/(kA))) where L is the distance between the two nodes, M is the mass of the load and k is a constant. Design a laboratory experiment to test the relationship between f and A. Explain how your results could be used to determine a value for k. You should draw a diagram, on page 3, showing the arrangement of your equipment. In your account you should pay particular attention to: • the procedure to be followed • the measurements to be taken • the control of variables • the analysis of the data • any safety precautions to be taken.