1. Using a Balancing Toy Pendulum for Teaching Rigid Body Dynamics Tetsuya YAMADA Shiga Prefectural Seta Technical High School Fumiyasu KURATANI Faculty of Education, Wakayama University Tadao YAMANO Hyogo University of Teacher Education

2. From Shiga Prefecuture JAPAN An inland industrial prefecture There is big Lake Biwa

3. At Technical High Schools in Japan Motion analysis as the foundation of kinetic design is not taken up. A balancing toy pendulum is introduced as a practical example of a rigid body.

4. Simple Structure The balancing toy is a traditional toy in Japan. It is simple structure. It isn't possible to move as the mind without the analysis.

5. A Balancing Toy Pendulum Changing the angle between the arms modifies the position of the center of gravity and the moment of inertia of this pendulum. Adjusting the machine screw in the center also modifies the distance between the position of the center of gravity and the supporting point.

6. Influence of the Center of Gravity and the Inertia Moment ・・・ (1) ・・・ (2) arm ’ s mass is neglected arm ’ s mass is taken into consideration

7. Comparison between Theoretical and Measured Values It is clear that the theoretical and the measured natural periods show good agreement. VIDEO 1 VIDEO 2

8. Lesson Practice 12 hours were spent on the lesson practice composed of subject explanation, theory explanation, motion analysis, design and making We indicated the production of the balancing toy pendulum having the natural period of 1 second

9. Design and Production Goal A target is the natural period of 1 second.

10. In the Report Almost all the students indicated the importance of analysis and design in manufacturing.

11. The Flowchart of Design and Making

12. CONCLUSIONS This presentation has proposed the method of teaching rigid body dynamics. A balancing toy pendulum was introduced as a practical example of a rigid body. The formula for calculating the natural frequency of a balancing toy pendulum was derived. The theoretical and the measured natural periods of the balancing toy pendulum showed good agreement.

13. CONCLUSIONS 2 The natural period as a feasible objective in the design and making was illustrated. The importance of analysis and design in manufacturing was highlighted by use this teaching material