You are standing in a moving bus, facing forward, and you suddenly fall forward as the bus comes to an immediate stop. the force acting on you that causes you to fall forward is a) the normal force due to your contact with the floor of the bus. b) the force due to static friction between you and the floor of the bus. c) the force of gravity. d) the force due to kinetic friction between you and the floor of the bus. e) no forces were acting on you to cause you to fall.

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.