Study of the scientific understanding of Newton’s Third Law of Motion for high school students

Abstract

This research aimed to develop a test and use it to investigate students’ scientific understanding of Newton’s Third Law. The sample group consisted of 74 upper secondary school students. The test was designed as an open-ended assessment in which students were required to draw free-body diagrams and indicate the magnitudes of action–reaction forces. The test consisted of four questions covering four learning objectives. The instrument was examined for quality in terms of content validity, discrimination index, and difficulty index by experts, and the results indicated that all items met the required standards. The findings revealed that students demonstrated an average correct understanding of 23%. The most common misconception was the belief that a car moving at a higher speed exerts a greater force, accounting for 82%. The second most common misconception was that because a truck has a greater mass than a car, the car exerts a greater force on the truck, accounting for 79%. The least common misconception, accounting for 70%, was the belief that the force exerted by the car is greater than that exerted by the wall.