A cylindrical rod of pure copper has density

PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A cylindrical rod of pure copper has density 8.9×103 kg m−38.9\times10^{3}\,\text{kg\,m}^{-3}. A longitudinal wave travels along it at 4.7×103 m s−14.7\times10^{3}\,\text{m\,s}^{-1}. After alloying with zinc, the density of the rod increases by 4%4\% and the measured wave speed becomes 4.6×103 m s−14.6\times10^{3}\,\text{m\,s}^{-1}. Answer the following: (i) Calculate the Young’s modulus of the rod before alloying. (ii) Determine the percentage change in Young’s modulus caused by alloying, correct to two significant figures.

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