3.6.1.3
Reducing errors in SHM practicals
Simple Harmonic Motion — AQA A-Level Physics
Systematic errors
- Reduce parallax error by viewing the fiducial marker at eye level.
- A motion tracker and data logger provide more accurate timing than a stopwatch.
Random errors
- Time 10 oscillations and divide by 10. This reduces the effect of reaction time.
- Keep amplitudes small (a few cm) to prevent non-SHM behaviour.
- For the pendulum: small angles only. Large angles violate the sin $\theta = \theta approximation$.
- For the mass-spring: check oscillations stay vertical. Repeat if the mass swings sideways.
Safety
- Place a soft surface below the equipment to catch falling masses or bobs.
- Only pull down a few cm to prevent masses detaching from the spring.
- Clamp the pendulum string tightly to prevent it slipping during oscillations.