Design a "bungee jump" apparatus for adults. a bungee jumper falls from a high platform with two elastic cords tied to the ankles. the jumper falls freely for a while, with the cords slack. then the jumper falls an additional distance with the cords increasingly tense. assume that you have cords that are 12 m long, and that the cords stretch in the jump an additional 19 m for a jumper whose mass is 120 kg, the heaviest adult you will allow to use your bungee jump (heavier customers would hit the ground).

Uranium has two naturally occurring isotopes. 238u has a natural abundance of 99.3% and 235u has an abundance of 0.7%. it is the rarer 235u that is needed for nuclear reactors. the isotopes are separated by forming uranium hexafluoride uf6, which is a gas, then allowing it to diffuse through a series of porous membranes. 235uf6 has a slightly larger rms speed than 238uf6 and diffuses slightly faster. many repetitions of this procedure gradually separate the two isotopes. what is the ratio of the rms speed of 235uf6 to that of 238uf6? express your answer to five significant figures.