1. Pendulum: a long, suspended body (bob) whose lower end moves back and forth when subjected
    to gravity.

2. Period: The time it takes the bob to make one complete back and forth trip on a pendulum

3. % Change:  a measure of the amount of change in data (expressed as a percentage) between trials in
    an experiment.

4. String Length of pendulum: measurement of amount of string connecting the bob mass to the
    apparatus.

5. Arc: the angle at which the pendulum’s bob mass is dropped from.