Galileo was the first person to study the motion of a pendulum, around the year 1600. He found that the time it takes a pendulum to complete a full swing depends only on the length of the pendulum. Galileo found that the period of a pendulum is proportional to the square root of its length T=2/T where T is the time in seconds it takes for the pendulum to complete 1 period and L is the length of the pendulum measured in meters. Definition of a Period: The time it takes a pendulum to complete one full back-and-forth swing. Below is a video of a pendulum on the UCF campus. If you watch the video, you'll notice that it takes approximately 8.5 seconds to complete a full period. Using this information, determine the length of the pendulum in meters.