楊氏係數測量實驗

1. 楊氏係數測量實驗

2. Stresses in Solids • The level of stress required to obtain a given deformation ※Tensile stress(伸長應力)，Tensile strain (伸長應變) and Young’s modulus (楊氏模數) ※Shear stress(剪應力)，Shear strain (剪應變) and Shear modulus (剪力模數) ※Volume stress(體積應力)，Volume strain (體積應變) and Bulk modulus (體積彈性模量)

3. Tensile stress(伸長應力)，Tensile strain (伸長應變) and Young’s modulus (楊氏模數) F⊥ F⊥ F⊥ F⊥

4. Stress應力-strain應變relationship 線性範圍

5. Young’s modulus (楊氏模數)，Shear modulus (剪力模數) ，Bulk modulus (體積彈性模量)

6. 光槓桿系統(Optical Lever) 鋼線 平面鏡 L0 C 雷射光源 腳尖 A,B 圓柱狀金屬栓 (鎖住鋼線) C 直尺 P A B

7. L0 ∆d C A,B Mg

9. End of Lecture

10. Shear stress(剪應力)，Shear strain (剪應變) and Shear modulus (剪力模數)

11. Volume stress(體積應力)，Volume strain (體積應變) and Bulk modulus (體積彈性模量)

14. 線性範圍

17. Shear stress(剪應力)，Shear strain (剪應變) and Shear modulus (剪力模數)

18. 血液動力學中的剪力

19. Volume stress(體積應力)，Volume strain (體積應變) and Bulk modulus (體積彈性模量)

20. Young’s modulus (楊氏模數)，Shear modulus (剪力模數) ，Bulk modulus (體積彈性模量)

21. Stresses in Fluids • Normal stress ( pressure ) compress or expand the fluid particle without changing its shape ※ Bulk modulus( 體積彈性模量) • Tangential or shearing stress shear the fluid particle and deform its shape ※ Viscosity ( 黏滯力 ) The viscosity of a fluid measures its ability to resist a shear stress.

22. The Nature of Fluids • The fluids cannot support Tensile stresses and Shear stresses . • The fluids flow and deform continuously and permanently under Shear stresses .

23. Young’s modulus (楊氏模數)，Shear modulus (剪力模數) ，Bulk modulus (體積彈性模量)

26. 黏滯應力 ( Viscosity Stress ) Momentum exchange by molecular mixing Viscosity Shear Stress ≡ Change in momentum in bulk fluids Viscosity Stresses tend to decrease the velocity of the flow on the high speed side of the layer, increase the velocity on the low speed side.

27. Velocity profile in the region near a solid surface. A shear layer near a solid wall du

28. Viscous effects particularly important near solid surfaces. Boundary layers Growth of a boundary layer along a stationary flat plate.

29. Laminar and Turbulent Flow

30. Figure 1.22 The no-slip condition in water flow past a thin plate. Flow is from left to right. The upper flow is turbulent, and the lower flow is laminar. With permission, Illustrated Experiments in Fluid Mechanics, (The NCMF Book of Film Notes, National Committee for Fluid Mechanics Films, Education Development Center, Inc.,1972).

31. Viscous Internal Flows

33. d r d x Laminar flow of viscous fluids in a circular pipe τ(y) dr τ, P r

34. u

36. Flow rate

38. Figure 1.17 A long flat plate moving at constant speed in a viscous fluid. On the left is shown the velocity distributions as they appear to a stationary observer, and on the right they are shown as they appear to an observer moving with the plate.

39. Surface Tension Cohesive forces≡attractive forces between molecules of the same type F =σ( 2 l )

40. ∆p Surface Tension • (a) Drop • (b) Bubble Equilibrium (a) drop and (b) bubble, where the excess pressure is balanced by surface tension.

42. Pa CapillarityAdhesive forces≡attractive force between molecules of the different type θ

44. Figure1.25 Angle of contact. (a) Free surface shape of water and mercury in glass tubes. (b) A wetting, and a non-wetting liquid.

45. Figure 1.26 A drop of liquid squeezed between two glass plates.

46. Home Work • 流體力學 • chapter 1 Introduction 19, 21, 22, 26, 27, 28, 29, 31 • chapter 9 Viscous Internal Flows 35, 36, 38 (a), 39 • chapter 29NMR 24, 25, 27, 29, 30, 31, 32, 33, 34, 35, 37, 39, 40, 41, 42, 43, 44