engleski

Probing students' conceptual knowledge of satellite motion by use of diagram

Regardless of wide use of satellites they are still often considered as “mysterious” objects, mostly because they travel in space where most of us have never been. So that developing an intuitive understanding of satellite motion remains out of our scope. That's probably why the dynamics of orbital motion proved to be conceptually difficult for students. Being aware of these conceptual difficulties, many years after he published Principia, Newton wrote a popular text to explain the orbital motion of the Moon. In this paper he demonstrated the significance of the velocity of the satellite as equally responsible for the orbital motion as the attractive gravitational force of the Earth [1]. He discussed the trajectory of a cannon ball which was launched horizontally from the top of a high mountain and, which was attracted by the Earth gravity. If the launch speed was increased enough, the ball would start orbiting the Earth. Besides, the gravitational force is directed toward the center of the Earth so that the center of the circular satellite orbit and the center of Earth should match. Two and half centuries later, students enter and leave the physics instruction with a wide variety of misconcepts about satellite motion. Many physics education researchers were aware of the importance of studying this topic which resulted in identification of many students’ misconceptions. In our study [2], we investigated students’ ideas about possible satellite orbits. And we have concluded following: 1) Students tend to use the p-prim [3] "closer is stronger" instead of applying physics knowledge ; 2) Regardless of their educational level and curricula, students in Croatia lack deep understanding of circular motion, gravitational force and first cosmic velocity. 3) The teachers considerably overestimate students’ abilities. References [1] I. Newton, A treatise of the system of the world (printed for F. Fayram, London, 1731). [2] N. Erceg, I.Aviani, V.Mešić, Z. Kaliman and D. Kotnik-Karuza, Rev. Mex. Fis. E 60 (2014) 75. [3] A. A. DiSessa, Cogn. Instr. 10 (1993) 105.

diagrammatic representation; satellite motion; students' problem solving

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