12 meter long uniform plank weighing 2000N balanced on fulcrum. if the 800N object is placed on the beam 1.5 meters from it's right end where, if it all, can the fulcrum be moved such that this new system remains level and in equilibrium?

A) the system cannot be in equilibrium unless another weight is added to the left side
B) the system cannot be in equilibrium because the beam ins't long enough
C) moving the fulcrum 1.3 meters to the right of the center will balance it
D) moving the fulcrum 0.6 meters to the right of the center of the beam will balance it

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.