Physics
An optical bench: lenses, mirrors, image formation.
An optical bench: lenses, mirrors, image formation. Paraxial thin-lens and mirror approximation.
Equations 1/u + 1/v = 1/f; m = −v/u y(x) = y₀ + θx; θ_after = θ_before − y/f u = f: v → ∞; f < 0: v < 0
Physics
A heavy ball on a rope from a rotating arm: it lags the arm and swings outward by inertia; cut the motor and the orbit spirals back in.
Physics / Astronomy
Roemer 1676: Io's eclipses arrive late when Earth is far from Jupiter, and the residuals of the fit measure the speed of light.
Physics
A bob swept round a cone: tension leans in, its horizontal part is the centripetal force, and only one spin rate holds the angle steady.