Your 1000-m-long starship has warning lights at each end that, to you, flash simultaneously every minute. you are moving directly away from the planet zerkon at 0.70c.
to a zerkonian, do the lights flash simultaneously? if not, which flashes first-the light at the front of your ship or the trailing one?

Atomic nuclei of almost all elements consist of

What is the gravitational attraction between a dating couple whose centers of mass are 0.630 m apart if the boy weighs 715 n and the girl weighs 465 n?

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.