The property that describes how radily a substance combines chemically with other substances is

Which best describes the difference between internal and thermal energy?

Aheavy boy and a lightweight girl are balanced on a massless seesaw. the boy moves backward, increasing his distance from the pivot point. what happens to the seesaw? it is impossible to predict without knowing additional information. the side the boy is sitting on will tilt downward. the side the girl is sitting on will tilt downward. nothing; the seesaw will remain balanced.

What is the period of a wave traveling 5 m/s if its wavelength is 20 m/s