A girl throws a pebble into a deep well at 4.0 m/s (downward). It hits the water in 2.0 s.
a. How far below the ground is the water's surface?
b. What is the pebble's average velocity?

Which statement is best supported by the information in the chart? wave y is moving the fastest. wave x is moving the fastest. all of the waves are moving at the same speed. all of the waves have the same value of wavelengths per second.

Aspacecraft that renters the earth’s atmosphere drastically slows down. the amount of kinetic energy the spacecraft has as it reenters the earths atmosphere

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.