Research of air resistance

1. Research of air resistance Koshi High School Oida RyosukeNakamura Kazuki

2. Research motive • Air resistance affects falling objects • When we can’t ignore air resistance, the faster the speed of a falling object, the higher the air resistance • When air resistance becomes equal to gravity, the object reaches terminal velocity • We want to research the relationship of terminal velocity and air resistance

3. Purpose of research • To research the relationship of terminal velocity and air resistance when an aluminum cup falls in the air • Why choose an aluminum cup? →Observation is easy Reaches terminal velocity immediately

4. Terminal velocity First only gravity affects the object When the object gains speed, it’s affected by air resistance At low speeds: R=kv R…air resistance v …terminal velocity k …constant

5. When the object reaches a fixed speed, air resistance and gravity are balanced and the aluminum cup falls at a constant speed This is called Terminal velocity

6. About air resistance① Air resistance force involves three things: 　　①Air resistance coefficient 　　②Surface area ③Speed For example Flat board1.2 Glove0.5 Prius　　0.26

7. About air resistance② resistance has viscous resistance and inertial resistance. viscous resistance・・・proportional to the speed inertial resistance・・・proportional to the square of the speed 　Ｒ＝kv　　　　　　　　　Ｒ＝kv２ Ｒis air resistance (in N)v is speed (in m/s) k is a constant of proportionality

8. experiment1

9. Purpose of the experiment１ We pile aluminum cups and increase the amount of mass. We look for changing resistance from changing terminal velocity and we search for the relationship 質量が増えたときの終端速度の変化から、抵抗力の変化を求め、その関係を調べる。

10. Experiment method • We recorded the aluminum cups falling along the experimental device. • The experimental device・・・it is a ruler attached to a board（メジャーを板に垂直に設置したもの） • We checked the video on a PC and we replayed each frame. We searched for the distance.アルミカップが決められたフレーム数で進む距離を求めた。 • Then we searched for how much the distance changed each second. 求めた距離を一秒間に進む距離に直し、終端速度とした。

11. Next, we piled aluminum cups and we did a similar experiment (figure1) Figure １　piled aluminum cups

12. Result of experiment 1

13. Graph of the results of experiment 1 Figure ２　（the results of experiment 2）

14. Discussion of experiment 1 • We expected「R=kv2」　　　→When we reduced the number of aluminum cups, we got good data. • When we increased the number of aluminum cups 　　　→The results are markedly different because the coefficient of air resistance changed

15. Experiment 2

16. Purpose of experiment 2 • Don’t change the shape of the object to be dropped • By increasing the mass, find the change in resistance from the change in terminal velocity, and examine the relationship

17. Experimental method • The increased mass of the aluminum cup with reference to FIG. 3 • We found the terminal velocity in the same manner as Experiment 1 Figure 3The folded aluminum cup that was placed

18. Result of experiment 2

19. Graph of the results of experiment 2

20. Discussion of experiment 2 • When we increased the number of cups, the graph was disturbed →Aluminum cups didn’t reach terminal velocity • The relationship was proportional to the square of the mass and speed

21. Conclusion • When aluminum cups are falling, air resistance forceis proportional to thesquare of the speed.

22. Future plans • We will change the conditions of the falling aluminum cup. • We will investigate the relationship between the speed and resistance of falling aluminum cups

23. Thank you for listening!