The investigative question for the pendulum lab was: Which of the 3 variables (amplitude, length or mass) is the key factor to make the pendulum have more frequent cycles? In order to find the key factor, let’s understand what a pendulum is.

The pendulum is a simple construction that consists of a bob, a fixed point and a thin line of string in between. If you were to pull back the bob (weight) from its original point at a 45 degree angle, it would start to build potential energy. Once you release the weight, gravity kicks in and gives the pendulum kinetic energy.

Furthermore, it has enough momentum and acceleration from the force of gravity to actually go past the original point. Once past the original point the earth’s rotation or inertia tries to put the pendulum back to its original position. This pattern continues on and on until you try to stop the pendulum. You can see many examples of pendulums in our daily life. For example, the grandfather clock, this has a pendulum that powers the clock’s mechanism. Another example would be a swing set, where the bob is the person who is sitting on the swing and the kinetic and potential energy comes from the person “swinging”.

The first variable that was tested was the weight. So our first hypothesis was: “If we increase the weight of the bob, then the number of periods (times the bob went back and forth) would go faster.” During our testing, we were using 3 different kinds of weights: 50, 100 and 200 grams. All of them are hanging on the same length (30 cm) and for each weight we counted how many periods (or cycles) there were in a 15 second period. Then after 15 seconds we multiplied the number of cycles by 4 to find out the cycles per minute.

During our experiment, the data shows that the frequency per minute remains the same regardless how heavy the bob was.

For that reason, we had to test the next variable: amplitude. Our new hypothesis was: “If you were to change the amplitude of the bob, then the pendulum will swing faster.” To test that hypothesis, we released the bob of the pendulum at different release points. The data has proven that the hypothesis