Physics · Oscillations · NEET
The mean position is the central rest point where the body would stay if it were not disturbed. In oscillatory motion the body moves on one side of this point, comes back, crosses to the other side, and returns again. For a pendulum, the mean position is the lowest point where the bob hangs at rest. The body always swings around this fixed point.
They mean the same basic idea: a to-and-fro motion about a mean position. By habit, we say 'oscillation' when the motion is slow and we can see it, like a pendulum or a swing. We say 'vibration' when the motion is very fast, like a guitar string or the atoms in a solid. Physics treats both the same way, so for NEET do not worry about the difference in the word.
Yes, an ideal oscillatory motion (with no friction or air drag) is always periodic, because each to-and-fro trip takes the same amount of time. But the reverse is not true: not every periodic motion is oscillatory. A planet going around the Sun is periodic (it repeats) but it is not oscillatory, because it does not move to-and-fro about a mean position. See periodic-vs-oscillatory-motion.
No. In uniform circular motion the body keeps moving in the same direction around a circle; it does not reverse and come back about a mean position. It is periodic (it repeats every round) but not oscillatory. Interesting point: the shadow (projection) of a body in uniform circular motion on a straight line does move to-and-fro, and that projection is simple harmonic motion.
SHM (simple harmonic motion) is a special, simplest kind of oscillatory motion. All SHM is oscillatory, but not all oscillatory motion is SHM. Oscillatory motion just means to-and-fro about a mean position. It becomes SHM only when the restoring force is directly proportional to displacement and always points toward the mean position (F = -kx). See what-is-simple-harmonic-motion.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It is a motion in which a body moves back and forth (to-and-fro) again and again about a fixed central point called the mean position, like a pendulum or a swing.
A simple pendulum swinging, a child on a swing, and a mass hanging from a spring bouncing up and down. Other examples are a boat rocking on water and the piston in a steam engine going back and forth.
Yes. An ideal oscillatory motion repeats after equal time intervals, so it is periodic. But not all periodic motion is oscillatory, because periodic motion need not be to-and-fro about a mean position.
Both are to-and-fro motions about a mean position. We usually call slow, visible motion an oscillation (pendulum) and very fast motion a vibration (guitar string). In physics they are treated the same.
Yes. Simple harmonic motion is the simplest type of oscillatory motion, where the restoring force is proportional to displacement and directed toward the mean position (F = -kx).
