Physics · Ch 10 — Oscillations
Oscillatory motion
Oscillatory motion
When an object or particle moves back and forth repeatedly about some reference position for a period of time, its motion is called oscillatory or vibratory motion. Familiar examples include the beating of the human heart, the rhythmic swinging of an insect's wings in flight, and the to-and-fro swing of a grandfather clock's pendulum. Every oscillatory motion is necessarily periodic, because moving back and forth about a fixed point automatically means the same position and state of motion recur after a fixed time interval. The converse, however, is not true: not every periodic motion is oscillatory. The Earth going around the Sun is periodic (it repeats every year) but it is not oscillatory, since the Earth does not move back and forth about a reference point -- it travels around a closed path in one sense only. So 'periodic' …
What this figure shows. A small collage of everyday oscillatory motions used to introduce the idea before any equations are written down: the rhythmic beating of a human heart, the rapid back-and-forth beating of an insect's wings in flight, and the swinging bob of a grandfather clock's pendulum. In every picture the moving part repeatedly reverses direction about a fixed central or reference position, which is exactly the property that defines oscillatory motion, as opposed to a motion like the Earth's orbit that repe …
What this figure shows. A second illustrative panel showing two of the canonical laboratory oscillators referred to throughout the rest of the unit: a block hanging from a coil spring, and a bob hanging from a string as a simple pendulum. Both are shown at their extreme displaced positions as well as passing through the equilibrium position, visually setting up the block-and-spring and pendulum systems that section 10.2 onward analyses mathematically as Simpl …