Which of the following has potential but not kinetic energy? (2 points) a roller coaster zooming down a hill

b child riding their bike

c bird flying from a tree

d ball sitting on a shelf

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.

Calculate a pendulums frequency of oscillation (in hz) if the pendulum completes one cycle in 0.5s.

Aball of mass 0.3kg is released from rest at a height of 8m. how fast is it going when it hits the ground? accleration due to gravity is g=9.8m/s