Quick overview: mechanics

Concept of inertia, and the causality of processes expressed through Newton's laws.
A big revolution in science; nowadays, this is how our everyday intuition is formed.
( An excellent example is provided by studying how objects move in gravity. )

Energy conservation is a general, rounded concept present everywhere in modern physics.
Examples from mechanics are used mostly to motivate it; there are many, various, forms of this principle.
( Something falling: its gravitational potential energy gets converted to kinetic energy. More useful: springs. )

We will make good use of two particular concepts / examples from mechanics.
Collisions: kinetic energy is transferred from a body with more to the one with less.
Springs: restoring forces oppose being pushed or pulled. (They push/pull back.)
Energy constantly oscillates between potential and kinetic forms.