Measuring “g” by using trajectory projectile motion: 5E learning cycle and low-cost materials

The purpose of this paper is to demonstrate how teachers can provide students an opportunity to measure “gravity” by observing and analyzing the trajectory of projectile motion in 2D. Another aim is to have students use the 5E learning cycle in this activity, which can be conducted with low-cost materials. In addition, it allows students to study the relationship between different factors such as air resistance and friction, which are in their cognitive competence. For example, students can explore and explain what kind of approximations they need to make. These approximations might be air resistance and friction. So, they can find out how these factors affect their results because they will get a different result from g=9.8 m/s². Of course, there are other factors that affect the result such as measurement errors. Students will learn to plan and conduct scientific investigations through studying the motion of a ball or a marble to measure “g”. This allows students to realize there is not just one fixed investigation method to follow while conducting investigations.

The activity was conducted in a PHYSWARE Collaborative workshop on low-cost and appropriate technologies that promote undergraduate level, hands-on physics education throughout the developing world. This paper records how the activity to measure g was set up and presented authors in the PHYSWARE workshop held in Italy in 2009. This workshop focused on mechanics teaching in physics topics. Although we developed various instructional materials as one is seen in this paper, created construction plans, and ideas for activities to help educators make effective use of both low cost and high technology equipment, only one, the trajectory projectile motion activity is discussed here.

This activity had also been run by Byansi in an undergraduate physics course. However, no formal research has been conducted to investigate students’ conceptual understanding, views, and performance of “g” measurement. Based on his observations, students were actively engaged and showed curiosity because it was not a traditional way of conducting an activity to measure “g” such as dropping a ball. It was a more creative way of measuring g. Use of the 5E learning cycle model to conduct the activity distinguishes it from traditional cookbook lab experiments. The 5E learning cycle model is an instructional model that provides active learning experiences and promotes student inquiry and exploration as a process of learning science. Students construct new understanding and develop new skills.