Conditions for SHM:
1. Small Amplitude Oscillations: The angle of displacement from the equilibrium position must be small (typically less than 10 degrees). This ensures that the restoring force is directly proportional to the displacement, a key requirement for SHM.
2. No Air Resistance or Friction: Any external forces like air resistance or friction will dampen the oscillations, making the motion deviate from SHM.
Why is it approximate SHM?
* The restoring force is not perfectly linear: The restoring force in a pendulum is proportional to the sine of the angle of displacement. For small angles, sin(θ) ≈ θ, making the force approximately linear. However, for larger angles, this approximation breaks down, and the motion becomes non-linear.
* The period of oscillation is dependent on amplitude: In true SHM, the period is independent of the amplitude. However, for a pendulum, the period increases slightly as the amplitude increases.
In Summary:
While a simple pendulum is often modeled as undergoing SHM, it's important to remember that this is an approximation valid only for small oscillations and in the absence of significant friction. For larger amplitudes, the motion deviates from pure SHM.
