The student requires only a few materials for this experiment including a lemon, a potato, a non-extensible cord, a stop watch and measuring tape. Ideally, the lemon and the potato should be regular-shaped, making it easier to attach them to the cord and perform the experiment. Students may experiment further by selecting potatoes and lemons of various sizes and shapes, and observing whether these variables influence the results in any way. In this case, the student should also get a scale to weigh the lemons and potatoes.
The project involves creating a simple pendulum. Tie the cord around the lemon first and attach the other side to a tall table or overhead bar. The student starts the pendulum and counts the number of oscillations, recording the time. The student records the time for the lemon and for a potato, then divides the time by the number of the oscillations he counted to obtain the time for oscillation. Repeating the experiment five to 10 more times will give the student an average value per oscillation for the lemon and for the potato.
The student compares the average results he obtains for a single oscillation for a lemon with the oscillation time of a potato. To expand the experiment, the student can test whether the size and weight of the lemon or potato play any role in the oscillation time. The student should also experiment using cords of different sizes. When comparing the results, the student should conclude that the weight and the size of the lemon and potato don't influence the time period of the pendulum, but the length of the cord will affect the time period.
Performing these experiments and obtaining the average values for the time period of the pendulum allows the student to obtain the value of the gravitational constant, also known as "g."
Using the formula for time period of a simple pendulum, T=2π√ L/g, the student can deduct the value of "g." In this formula "T" stands for the time period of a simple pendulum, while "L" is the length of the pendulum. The student compares his findings with the standard value of 9.8 that scientists use when referring to objects located on Earth.