The idea of this labour is to determine how the length of a pendulum affects the time of each swing.
Things Required:
String
Washer
Scissors
Ruler
Heavy book
Table
Stop watch or watch with a second hand
Helper
Directions:
Cut a string the height of the table. Tie one end of the string to the washer, and use tape to attach the other end of the string to the end of the ruler. Lay the ruler on the table with about 4 inches (10 cm) of the string extending over the edge, and the string hanging freely. Lie the book on top of the ruler to hold it in place. Pull the washer to one side and release it.
Ask your helper to start the timer as you count the number of swings in 10 seconds. Shorten the string by one-fourth its length. Pull the washer to one side, release it, and count the number of swings in 10 seconds as your helper records the time.
This Is What Happens:
The number of swings doubles with the shorter string.
Science Behind It:
Galileo has been credited for discovering the relationship between the length of a pendulum and the time of its swing. The story told is that he observed the swinging of a great lamp while in church and timed the swings by comparing them with his pulse beat. He later discovered that the time of a swing depends on the length of the pendulum and that the time decreases by one-half if the string is one-fourth the original length.
