1. 講者： 許永昌 老師 1

2. Contents Goal of this chapter Action: K and W Action: Work is  Fcos  dr=  F  dr. Work-Kinetic Energy Theorem Conservative and Nonconservative forces Conservation of Energy Power 2

3. Goal of this chapter 3

4. Energy Transfer and Energy transformation ( 請預讀 P303~P304) 4 E th KU SYSTEM Energy transfer

5. Action: K and W ( 請預讀 P302~P306) 5 F F

6. Action: Work done by a force F is  Fcos  dr ( 請預讀 P307~P309) 6 

7. The dot product of two vectors ( 請預讀 P310~P311) Geometric: Algebra: E.g. A=(1, 1) B=(sqrt(3), 1) A  B=? 請同時使用兩種算法算看看。 7 A B A B A B

8. Exercise of work-kinetic energy theorem A 2.0 kg ball is lifted upward on a string. It goes from rest to a speed of 2.0 m/s in a distance of 1.0 m. What is the tension (assumed to stay constant) in the string? Method 1: by Newton’s 2 nd Law of Motion Method 2: by Work-Kinetic Energy Theorem. 8

9. Homework Student Workbook 11.1, 11.2, 11.3, 11.9, 11.12 9

10. Summary I 10

11. Conservative and Nonconservative force ( 請預讀 P312~P316) 11 A B A B

12. Conservative and Nonconservative force (Continue) 12

13. Exercise A 1.0 kg block whose velocity is v x =2.0 m/s at x=0 m moves along the x-axis. Assume that there is only one kind of force exerted on this block and F x -versus-x graph is shown as follows. Calculate the velocity of this block at x=5 m or it never gets to x=5 m. Plot the potential-versus-x graph. 13 x (m) F x (N)

14. Finding force from potential energy ( 請預讀 P317) Since we get Therefore, 14 梯度

15. Homework Student Workbook 11.14, 11.15, 11.17, 11.19, 11.21 15

16. Summary II 16

17. Center of Mass ( 請預讀 P343) Based on Newton’s 2 nd and 3 rd Law of Motion: If we define We get 17 X

18. Kinetic Energy 18 X X X 考慮旋轉時，會把 K rot 由 K micro 中抽離出， 也當作 Kmech 中的一個。

19. Potential energy contributed from the internal forces 19

20. System and Environment ( 請預讀 P318~P322) Work-kinetic energy theorem: W net =  K. K=K macro +K micro. W net =W c +W nc W c =  U mech  U micro W nc =W ext ( 這裡與課本不同的是， dissipative force 在微觀尺度其實也是來自 保守力，所以已經被計算在 U micro 裡頭了 ) We get: 20

21. System and environment ( 請預讀 P323~P324) Work-kinetic energy theorem 21 Conservation of Energy System W Q Wave, …

22. Power ( 請預讀 P325~P327) 22

23. Exercise A 0.5 kg cart and a 2.0 kg cart are attached and are rolling forward with a speed of 2.0 m/s. Suddenly a spring-loaded plunger pops out and blows the two carts apart from each other. The smaller cart shoots backward at 2.0 m/s. What are the speed and direction of the larger cart? If the spring constant of the plunger is 25,000 N/m, by how much was the spring initially compressed? 23

24. Summary III 24

25. Homework Student Workbook 11.22, 11.23, 11.25, 11.26. Textbook 11.11 11.28 11.35 11.38 11.50 11.59 請自行練習 Terms and Notation ( 製造字卡 ) 25