## Wednesday, April 7, 2010

### PEKA - Form 4 - PENDULUM

Aim of the experiment:
To investigate how the period of a simple pendulum varies with its length.

Hypothesis:
The longer the length of a simple pendulum, the longer the period of oscillation.

Variables:
Manipulated: The length of the pendulum, l
Responding: The period of the pendulum, T
Constant: The mass of the pendulum bob, gravitational acceleration

Apparatus/Materials:
Pendulum bob, length of thread about 100 cm long, retort stand, stopwatch

Setup:
Procedure:

1. The thread is tied to the pendulum bob. The other end of the thread is tied around the arm of the retort stand so that it can swing freely. The length of the pendulum, l is measured to 80 cm as per the diagram.
2. With the thread taut and the bob at rest, the bob is lifted at a small amplitude (of not more than 10°). Ensure that the pendulum swings in a single plane.
3. The time for ten complete oscillations of the pendulum is measured using the stopwatch.
4. Step 3 is repeated, and the average of both readings are calculated.
5. The period of oscillation, T is calculated using the average reading divided by the number of oscillations, i.e. 10.
6. T2 is calculated by squaring the value of T.
7. Steps 1 to 6 are repeated using l = 70 cm, 60 cm, 50 cm, and 40 cm.
8. A graph T2 versus l is plotted.
Data:
Analysis :

Discussion:
The graph of T2 versus l shows a straight line passing through the origin. This means that the period of oscillation increases with the length of the pendulum, with T2 directly proportional to l.

Conclusion:
The longer the length of the pendulum, the longer the period of oscillation. The hypothesis is proven valid.

Precaution :
The experiment was carried out in an enclosed room to avoid the influence of wind.