One mole of nickel (6.02 ✕ 1023 atoms) has a mass of 59 g, and its density is 8.9 g/cm3. You have a bar of nickel 2.46 m long, with a square cross section, 1.9 mm on a side. You hang the rod vertically and attach a 43 kg mass to the bottom, and you observe that the bar becomes 1.5 mm longer. Next you remove the 37 kg mass, place the rod horizontally, and strike one end with a hammer. How much time t will elapse before a microphone at the other end of the bar will detect a disturbance