A cat that weighs 55 N sits on the top of a cat tree. It is 2 m above a 110N dog. How does the mass of the animals relate to the force of gravity on
them?
A. The 55 N cat has less mass than the 110 N dog.
B. The mass of the 55 N cat will be the same as the mass of the 110
N dog after it jumps to the ground.
C. The mass of the 55 N cat is greater than the mass of the 110 N
dog.
D. The 55 N cat has the same mass as the 110 N dog when it is in the
cat tree.

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.