SHM

Overview

This lesson introduces simple harmonic motion as a specific model for oscillations. The key idea is that the acceleration is proportional to displacement from equilibrium and always acts in the opposite direction.

What You Need to Know

• Displacement is measured from the equilibrium position, not from the end of the motion.
• Amplitude is the maximum displacement from equilibrium.
• Period and frequency describe the timing of repeated oscillations.
• SHM requires acceleration towards equilibrium, with acceleration proportional to displacement.

How to Work Through It

1. Label displacement, amplitude, and period on displacement-time graphs.
2. Compare different oscillating systems and decide whether the SHM condition is met.
3. Practise describing the direction of acceleration at different points in the motion.
4. Link angular frequency to period and frequency before using the equations in the next lesson.

Check Your Understanding

• Where is the acceleration greatest in SHM?
• What is the acceleration at the equilibrium position?
• How can you tell from words or a graph whether the acceleration is acting in the restoring direction?

Common Mistakes

• Calling every oscillation SHM without checking the acceleration-displacement relationship.
• Measuring displacement from the wrong reference point.
• Confusing phase difference with a time difference without considering the period.

Next Steps

• Secure the definitions before moving into the SHM equations.
• Practise explaining the SHM condition in one clear sentence.