An aluminium wire, of length l1 = 60.0 cm, cross-sectional area 1.00 x 10^-2 cm^2, and density 2.60 g/cm^3, is joined to a steel wire, of density 7.80 g/cm^3 and the same cross-sectional area. The compound wire, loaded with a block of mass in = 10.0 kg, is arranged as shown so that the distance ?2 from the joint to the supporting pulley is 86.6 cm. Transverse waves are set up in the wire by using an external source of variable frequency not shown in the picture: a node is located at the pulley. 1) Discover the lowest frequency of excitation for which standing waves are observed such that the joint in the wire is a node. 2) How many nodes are observed at this frequency?