You will need:
You've repeated an experiment that was first discussed by Galileo Galilei (1564 - 1642)! The story goes that he was watching a swinging bronze chandelier in a cathedral in Pisa and he noticed that a pendulum swing always follows the same arc. By using his own pulse he could time how long the period of the pendulum swing was. Galileo recognised that over time the swinging of the bronze chandelier would stop (conservation of energy) and that when repeating this experiment with a string and mass you could see that it was the length of the string rather than the mass that affects the period of a pendulum... i.e, the longer the string the longer the pendulum period.
For those who want to calculate what is going on, the period of oscillation of a simple pendulum is
T = 2π√(l / g) where:
T = time period for one oscillation (s)
l = length of pendulum (m)
g = acceleration due to gravity (m/s-2)
But why does the mass have no effect on the pendulum period? Because all materials accelerate towards Earth at the same rate!
This simple science experiment was used by the psychologist Piaget in 1958 to determine if children could isolate and test variables one at a time to experimentally test an idea (also called formal operational thinking). Children who struggled with this experiment were found to change more than one variable at a time whilst running the pendulum experiment and as such produce the incorrect answer that it is the mass at the end of the string that influences the speed of the pendulum. It's all about variable testing!
You can find applications of pendulums in a variety of places: