VIBRATION OF THE PENDULUM

Bab IV. Vibration and Wave.
VIBRATION OF THE PENDULUM
I. Objective:
To study the period of vibration of the pendulum.
II. Equipment and Materials:

a. A pendulum.
b. A static.
c. A stop watch.
d. Two lengths of nylon strings 30 cm and 60 cm.

III. Basic theory:
All bodies will vibrate if we give a displacement or a disturbance. Some vibrating object can be seen by naked eyes because the displacement we gave is large. Meanwhile, some others cannot seen by naked eyes because the displacement given very small.
Like as figure 1. A simple pendulum is initially rest at the position O (an equilibrium position). The pendulum is pulled to the position A (given a displacement). When the pendulum is free from position A, the pendulum will oscilaate regulary through the equilibrium point. The motion of pendulum from A to B to O and back to A (A-O-B-O-A) is called a full vibration.The motion of the pendulum from A-O-B is called a half vibration.
.
Figure 1.
So, vibratin is define as the oscilating motion of the body regulary through the equilibrium point. ( Prasodjo, Budi ;2009 : 129)
IV. Procedures
1. Bind the pendulum at to static so that it hangs.
2. Pull the pendulum to one side to give displacement to the pendulum, and then loose! At the moment pendulum is loosening, turn the stopwatch on.
3. Write the time that is shown by the stopwatch when the pendulum oscilates (vibrates) as 5, 10, 15, 20 vibrations.
4. Change the size of the string to be longer or shorter, and then repeat the step 3.
5. Write your data to observation table.
V. Observation Table.
Length of string ( cm) Number of Vibration Period of Vibration
30 cm 5 ...
10 ...
15 ...
20 ...

60 cm 5 ...
10 ...
15 ...
20 ...

VI. Question
1. Whats the relationship between length of string and period of vibration?
2. What is your conclution about from the activity above?