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Edexcel AS Physics Unit 1 : Chapter 7: Solid Materials Prepared By: Shakil Raiman.

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Presentation on theme: "Edexcel AS Physics Unit 1 : Chapter 7: Solid Materials Prepared By: Shakil Raiman."— Presentation transcript:

1 Edexcel AS Physics Unit 1 : Chapter 7: Solid Materials Prepared By: Shakil Raiman

2 7.1 Elastic Deformation  A material undergoing elastic deformation will return to its original dimensions when the deforming force is removed.  Example: Spring, Steel wire etc.

3 7.2 Plastic Deformation  A material undergoing plastic deformation will not return to its original dimensions or remain deformed when the deforming force is removed.  Example: modelling clay

4 7.3 Elastic and Plastic Deformation  Some material can behave in an elastic or plastic manner depending on the nature of the deforming force.  A thin steel sheet will deform elastically when small forces are applied to it, but the huge forces of a hydraulic press will mould the sheet into car panels.

5 7.4 Properties of Solid Materials  Hardness: Hardness is a surface phenomenon. The harder the material, the more difficult it is to indent or scratch the surface.  Diamond is hardest which has a rating 10.  Stiffness: A stiff material exhibits very small deformations even when subjected to large force.  Steel etc.

6 7.4 Properties of Solid Materials  Strength: An object is strong if it can withstand a large force before it breaks.  Steel is strong but cotton is weak.  Malleability: A malleable material can be hammered out into thin sheets.  Gold

7 7.4 Properties of Solid Materials  Ductility: Ductile materials can be drawn into wires.  copper

8 7.5 Stress  Stress (tensile/compressive stress) is defined as force per unit cross-sectional area.   Unit: Pa (Pascal)

9 7.6 Strain  Strain is defined as extension per unit original length.   Unit: no unit

10 7.7 Young’s Modulus  Young modulus is defined as the ratio of tensile or compressive stress to strain.   Unit: Pa (Pascal)

11 7.8 Hooke’s Law  Hooke’s law states that, upto a given load, the extension of a spring (or wire) is directly proportional to the force applied to the spring (or wire)   where K represents the stiffness or spring constant

12 7.9 Elastic Potential Energy or Elastic Strain Energy  The elastic potential energy or elastic strain energy is the ability of a deformed material to do work as it regains its original dimensions. 

13 7.10-1: Stress-Strain Graph

14 7.10-2: Stress-Strain Graph  O-A represents the Hooke’s Law region. Strain is proportional to stress up to this point. The Young modulus of material can be found directly by taking the gradient in this section.  B is the elastic limit. If the stress is removed below this value, the wire returns to its original state.

15 7.10-3: Stress-Strain Graph  C is the yield stress. For stresses greater than this, the material will become ductile and deform plastically.  D is the maximum stress that a material can endure. It is called ultimate tensile strength (UTS).  E or F is the breaking point. After E the wire starts narrowing.

16 7.10-4: Stress-Strain Graph

17 7.10-5: Stress-Strain Graph

18 7.10-6: Stress-Strain of Rubber The hysteresis loop for stress- strain graph represents the energy per unit volume transferred to internal energy during load- unload cycle.

19 Thank You All  Wish you all very good luck and excellent result.


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