Simple Harmonic Motion — A/L Physics

Simple Harmonic Motion (SHM) A periodic motion where the restoring force is directly proportional to the displacement from equilibrium and acts opposite to it. In SHM, acceleration is always directed towards the equilibrium position and is proportional to displacement: a ∝ -x . A mass on a spring or a simple pendulum (small angles) are classic examples. Intuition: the further you pull the system from rest, the stronger it pulls back.

Amplitude (A) The maximum displacement from the equilibrium position. Amplitude is a positive constant for a given oscillation. It determines the energy of the system (energy ∝ A²). For a pendulum, amplitude is the maximum angular displacement; for a spring, it is the maximum stretch or compression.

Period (T) and Frequency (f) Period is the time for one complete oscillation; frequency is the number of oscillations per second. They are related by T = 1/f . In SHM, period depends only on system properties (mass, spring constant, length) and not on amplitude. For a pendulum, longer length → longer period; for a spring, larger mass → longer period.