# What really is oscillatory motion in physics? [duplicate]

Is it that oscillatory motion must be to-and-fro motion about a mean/stable equilibrium position, or it does not qualify as true oscillatory motion? Or, is it that most of the oscillatory motion has a mean/stable equilibrium position, about which is it does to-and-fro motion, but it is not a must condition/not necessary, to qualify as oscillatory motion?

Examples that are making me more confused - a ball bouncing between two walls (100% elastic), a ball bouncing off the ground (100% elastic) etc.

Are these oscillatory motion?

What really is oscillatory motion to be very specific, and what are the strict conditions for a motion to qualify for oscillatory motion?

• Why not start here Oscillation? Commented Jan 25 at 16:30
• Does this answer your question? Is bouncing ball (100% collision) an oscillatory motion/SHM or both or none?
– Puk
Commented Jan 25 at 17:08
• Look, here's the thing. Your question (and your other questions!) is just about semantics (definitions of words) and not about physics. Sometimes, when people say "oscillations", they mean "simple harmonic motion", in which case the motion is sinusoidal motion about an equilibrium position. Sometimes, by "oscillation", people mean periodic (not necessarily sinusoidal) motion about an equilibrium position. And sometimes, by "oscillation", people mean that the motion is periodic (like a perfectly elastic bouncing ball). There is no strict definition, and you must reason from context. 1/2 Commented Jan 25 at 17:13
• All of that said, I would say that most of the time, when people use the word "oscillation", they are usually just referring to the fact that the motion repeats. People will add the word harmonic to imply that the motion is sinusoidal. And then you can reason from the physical context as to whether or not there is such a thing as an equilibrium position. (By the way, there is an equilibrium position in the bouncing-ball problem: it's the ground: if the ball sits on the ground, it just stays there.) 2/2 Commented Jan 25 at 17:13

Oscillatory motion, in physics, refers to a repetitive, back-and-forth movement around a central point or equilibrium position. This type of motion is characterized by a regular pattern of variation in a quantity, such as displacement, velocity, or acceleration, over time. The central point around which the motion occurs is often referred to as the equilibrium position or the mean position.

Common examples of oscillatory motion include:

Simple Harmonic Motion (SHM): This is a special type of oscillatory motion where the restoring force acting on an object is directly proportional to its displacement from the equilibrium position and is directed toward the equilibrium position. The classic example of SHM is the motion of a mass-spring system.

Pendulum Motion: A pendulum swinging back and forth is another example of oscillatory motion. The motion of a pendulum can be approximated as simple harmonic motion for small angles.

Vibrations: Oscillatory motion is also observed in vibrations, where an object oscillates about its equilibrium position. Examples include the vibrations of guitar strings or the oscillations of particles in a medium, like air or water, when sound waves are propagated.

Waves: Waves are a form of oscillatory motion that involve the transfer of energy through a medium. Examples include water waves, sound waves, and electromagnetic waves.

The key characteristics of oscillatory motion include amplitude (maximum displacement from equilibrium), frequency (number of oscillations per unit of time), and period (time taken for one complete oscillation). The mathematical description of oscillatory motion often involves trigonometric functions, such as sine and cosine, especially when dealing with simple harmonic motion.