Which takes place as water cycles from the bottom of the pot towards the top

A1200 kg car traveling north at 10 m/s is rear-ended by a 2000 kg truck traveling at 30 m/s. what is the total momentum before and after the collision?

Critical mass is the of material required to produce a chain reaction. a.) minimum amount b.) atomic mass c.) precise amount d.) maximum amount

In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. what is the electron's orbital frequency? what is the effective current of the electron?