1. A steel cable with total length 20m and mass 100kg is linked to two poles. The tension in the cable is 2,000 N, and the wind makes the cable vibrate by a frequency of 2 Hz. Compute the wavelength of the resulting wave on the cable.
2. A person stands at a point 510 m in front of the face of a sheer cliff. If the person shouts, how much time will elapse before an echo is hard? Suppose normal air pressure.