A certain steel has a density of 7700 kg/m3 and Young's modulus E = 210 GPa. A 20 mm diameter cable made of this material is used to lower a cage of mass 1000 kg down a mine shaft from a winch at ground level. What is the extension of the cable when the cage is 1 km below the surface. At this point, a miner of mass 100 kg gets into the cage. How much further will the cage descend as he gets in, assuming there is no brake to prevent this motion.