Measuring Earth's Properties

Overview

Objectives/Goals The goal of my science fair experiment is to measure some of the physical properties of our planet. In particular, I focused on measuring the Earth's gravitational acceleration. Methods/Materials I constructed a pendulum to help me measuring the gravity acceleration. With the pendulum I tested my hypothesis which was, If I used a longer string then the pendulum would swing back and forth for a longer amount of time. I tested multiple string lengths with some weights. When I was done,using my experiment results, I used the equation modeling the pendulum dynamics to calculate the gravity acceleration. Thirteen experiment sets were executed with two different values of weights (91.05 g & 128.45 g), two different lengths of the string (153 cm & 42.53 cm) and 4 displacements from the equilibrium (2,5 cm;5 cm;10 cm;15 cm). The weight consisted of one small orange( I originally wanted to use an apple in honor of Sir Isaac Newton but the apple was over the maximum weight that could be measured by the precision digital scale I used). Results During each experiment sets, I executed three experiments. During each experiment I measured with a stop-watch the time of ten oscillations. Finally I took the average of the three experiments and divided by ten in order to obtain the average time of oscillation during each experiment set. I made seven qualitative observations and one quantitative observations (computation of an estimated value of the gravity acceleration). Conclusions/Discussion For this experiment, my hypothesis was that a longer string will cause the pendulum to go back and forth in a longer amount of time, with respect to using a shorter string. After doing the experiment and looking through my observations, I found that my hypothesis is correct. It is true that if I use a longer string it takes the pendulum a longer amount of time to go back and forth. By using the experimental observations I computed an estimated value of the local gravity acceleration. In particular, I obtained the following estimated value of the local gravitational acceleration g=9.82 m/s2 (notably this value is very close to the most accurate one reported in physics books which is 9.80665) What i got from the equations was reasonably close to the actual one. Also my hypothesis is correct.

Competition history

• CSEF 2017 Physics & Astronomy · Entry J1816

Resources

• CSEF project summary ↗

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