it depends upon what state they are in like in motion or res
Reactions occur when two or more molecules interact and the molecules change. Bonds between atoms are broken and created to form new molecules. That's it.
I believe it is called an ampere.
For an object moving in a path that's a circle or a part of one,
the centripetal force acts in the direction toward the center of
the circle. That direction is perpendicular to the way the object
is moving.