For most of history the heavens and the Earth were thought to be different realms, each moving by its own rules. The great achievement of the seventeenth century was to see that they are one: that a single, small set of laws governs a rolling ball, a falling apple, and the orbit of the Moon alike. That vision is what we call classical mechanics.
The clockwork idea
Isaac Newton showed that motion is not capricious but lawful. Give the laws the position and velocity of every object now, and the future is fixed: the whole system unwinds like a wound clock. This picture, the clockwork universe, was so powerful that thinkers came to imagine the cosmos as a vast, precise mechanism, every gear meshing according to rule.
What mechanics studies
Mechanics is the study of motion and its causes. It asks how objects move, why they speed up or slow down or change direction, and what stays the same as they do. Its answers rest on a few ideas we will build in turn: force (a push or pull), mass (how much a thing resists being pushed), energy (the currency of change), momentum (a measure of motion that is conserved), and gravity (the force that reaches across space).
Why it still matters
Newton's mechanics was eventually found to have limits: it breaks down at speeds near light (where Einstein's relativity takes over) and at the scale of atoms (where quantum theory rules). But within the enormous range of ordinary experience it is essentially exact, and it remains the foundation of engineering and everyday physics. When you design a bridge, launch a rocket, or predict an eclipse, you are using the clockwork Newton built. This course assembles it piece by piece: the laws of motion, then energy, momentum, gravity, and finally the orbits that first revealed the whole scheme.