Wednesday, April 13, 2011

Lab Report: Soaring Straws

In science class, we conducted a lab that compared and contrasted between elastic potential energy (EPE) and gravitational potential energy (GPE). EPE occurs when an object is stretched back and has the potential to do work. On the other hand, GPE occurs when an object is at still point and has the potential to do work. In addition, potential energy can change into kinetic energy, or energy that it is motion. With this in mind, there are also some comparisons between GPE and EPE. The greater the EPE the greater the GPE. This statement can be proved because of the "Soaring Straws" experiment. Constantly, my partner and I saw how the more you stretched the rocket launcher the higher it would go. The manipulated variables throughout the lab were the rocket, the way we stretched the rocket, and the amount of stretch per trials. In the first set of trials, we constantly stretch the rocket launcher 10 cm. In result, the average height that the rocket reached was 2.95 meters. The average GPE was 52.1 mJ and we found this by multiplying the mass of the rocket(1.8g) by the gravitational acceleration (9.81) by the average height(2.95m). In the second set of trials, the amount of stretch was 7 cm. From this, the average amount of height reached by the rocket was 2.42m and the constant GPE was 42.73mJ. Finally, in the third set of trials, my partner and I constantly stretched the 2 cm. From this, the average height was 1.5 m and the GPE was 26.48 mJ.

Even though my partner and I tried our best to make the information as accurate as possible, we couldn't successfully accomplish this feat. First, the GPE is not accurate because you only substitute the gravitational acceleration with 9.81 when you are sea-level, and my partner and I didn't know exactly where we were at sea-level. Second, we couldn't accurately determine the height the rocket reached per trial the peak of it's movement was difficult to actually see so we estimated exactly where it was. Third, the more and more trials we conducted, the more and more our rocket launcher got damaged. Therefore, the later trials are inaccurate because our weak rocket launcher couldn't handle the toll it was taking. A better way to do the project next year is to rebuilding the rocket launcher every day so they can perform to their best and we can get accurate results. All in all, this project showed me how EPE and GPE compare and contrast through a fun and interactive lab.