Simple pendulum: finding g
A/L Physics · G.C.E. Advanced Level · Grades 12–13
Aim
To find the acceleration due to gravity g using a simple pendulum.
Apparatus
- Pendulum bob, thread and stand
- Metre rule
- Stopwatch
Method
- Set the length L from the point of suspension to the centre of the bob.
- Displace by a small angle (< 10°) and release.
- Time 20 oscillations, t, and work out T = t ÷ 20.
- Repeat for different L and calculate T².
- Plot T² against L; the gradient = 4π² ÷ g.
Conclusion
T² ∝ L (a straight line through the origin). g = 4π² ÷ gradient ≈ 9.8 m s⁻².