Two cables of equal diameter and length, one made of aluminum and the other made of steel, are welded together and strung horizontally under tension. When the aluminum end is struck, a wave pulse propagates from the end at a velocity of 15 m/s.

(a) The wave pulse crosses over the weld and onto the steel part of the cable. What is the velocity of the wave as it travels in the part made of steel??

(b) If the total length of the cable is 10 m, how long does it take the wave pulse to reflect off the far end and return? Note that these are not sound waves, but transverse waves like those on a string. Also, you may want to consult Table 10.1 for the densities of aluminum and steel.

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TABLE 10.1 Densities of Some Common Solids, Liquids, and Gases Density (kg/m') Substance SOLIDS Ice (at 0°C) 917 Aluminum 2,700 Lead 11,300 Platinum 21,500 Gold 19,300 Tungsten 19,300 Steel 7,800 Concrete 2,000 Bone 1,500-2,000 Polystyrene 100 Glass 2,500 Wood (spruce) 400 Wood (balsa wood) 120 Wood (oak) 750 LIQUIDS Water (0°C) 999.8 Water (4°C) 1,000.0 Water (20°C) 999.9 Seawater 1,025 Ethanol 790 Mercury Oil 13,600 700-900 GASES Air (0°C) 1.29 Air (20°C) 1.20 Air (100°C) 0.84 Helium (0°C) Hydrogen (0°C) Carbon dioxide (25°C) 0.18 0.090 1.80