1.7 Investigation of the relationship between period and length for a simple pendulum and hence calculation of g Outline of experiment
In this experiment, we will calculate a value for acceleration due to gravity (g). The experiment is based on simple harmonic motion of a periodic pendulum.
We can use either a graph or a formula to calculate g from this experiment. It is a simple, yet very accurate, method of determining g.
Equipment required Retort stand, stopwatch, string, split cork, bob pendulum mass retort stand mass (’bob’) split cork string
stopwatch/timer
M1.7a Investigating the relationship between period and length for a simple pendulum and hence calculating g
Method
1. Attach one end of the string to the pendulum bob and secure the other end between the split cork in the retort stand, as shown in M1.7a.
2. Record the distance between the point of suspension and the centre of the bob mass. (This should preferably be greater than 40 cm to reduce errors.)
3. Carefully hold the bob to one side and allow it to swing within one plane at an angle of no more than 5˚.
4. Using the stopwatch, record the time it takes for 50 oscillations. (Each oscillation is a swing from one side to the other and back again.)
5. Repeat the experiment for different lengths. 6. Transfer the data to the table. 7. g can be calculated from both the graph and the formula.
Length (m) T (50 oscillations) T (1 cycle) T2 l/T2 Characteristic graph
