One mole of nickel (6.02?1023atoms) has a mass of 59 g, and its density is 8.9 g/cm3. You have a bar of nickel2.60m long, with a square cross section,1.9mmon a side. You hang the rod vertically and attach a39kgmass to the bottom, and you observe that the bar becomes1.3mmlonger. Next you remove the 39 kg mass, place the rod horizontally, and strike one end with a hammer. How much timeTwill elapse before a microphone at the other end of the bar will detect a disturbance? (Assume a simple cubic lattice for nickel.)