Procedure Set up apparatus as illustrated in Fig 7.2. Pull the Newton weights down a small distance and release.
Observation The weights oscillate up and down.
Conclusion By analysing the motion using the motion sensor, data logger and calculator it can be seen that the weights are undergoing simple harmonic motion.
Newton weights
Motion sensor Calculator
Clamp Retort stand Spring
Logger Fig 7.2 Simple Pendulum
It can be proven that a simple pendulum swinging through a small angle of oscillation has a periodic time given by the equation:2
T periodic time, l length of pendulum, g acceleration due to gravity T 2pA
SIMPLE PENDULUM l
g SAMPLE PROBLEM 7C
Calculate the period for a simple pendulum of length 80 cm swinging through a small angle of oscillation, given that acceleration due to gravity is 9.8 m s2.
SAMPLE ANSWER 7C Using the formula for period of a simple pendulum, making sure all values are in their standard unit: l
T 2pAg 2pA The period of oscillation is 1.8 s.
0.8 9.8 1.8
2Proof is on the website www.gillmacmillan i.e for illustrative purposes as it is not subject to examination. However, two of the assumptions made in it are relevant for Mandatory Experiment 7, highlighted in the precautions for the experiment.
