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 Solids › Deformations › Stress › Strain › Elasticity  Fluids › Pressure.

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Presentation on theme: " Solids › Deformations › Stress › Strain › Elasticity  Fluids › Pressure."— Presentation transcript:

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6  Solids › Deformations › Stress › Strain › Elasticity  Fluids › Pressure

7  Anything that occupies space and has mass. › Volume › Mass › Density  Exhibits gravitational attraction  Has inertia

8  Solid  Liquid  Gas  Plasma  Supersolids  Superfluids

9  Elasticity  Malleability  Ductility  Plasticity  Strength  Hardness  Flexibility

10  Elastic and plastic materials are both deformed when subjected to force  Difference: › Elastic: material returns to its original dimension when force is removed › Plastic: deformation is permanent  Elastic materials may exhibit plasticity.  When and how?

11  Both are determined by the crystal lattice of the metal, and the strength of the bond between molecules of the metal  Copper is malleable and ductile. Aluminum is malleable but not as ductile as copper.

12  In the general use, they are the same; the ability o a material to resist deformation  Concrete is hard but it may not be as strong as metal.  Hardness … deformation due to compression  Strength … deformation due to tension

13  Also known as Law of Elasticity  Robert Hooke  For relatively small deformations, the magnitude of deformation is directly proportional to the deforming force  For relatively small deformations, the magnitude of deformation is directly proportional to the deforming force.

14  Conditions that fall under Hooke’s Law › Relatively small deformation › Deformation is within the elastic limit › The material returns to its original dimension when the force is removed

15  Greater deformation requires greater force.  The ratio of these too defines the elasticity of the material

16  Deformation will now be called strain in our analysis, and the deforming force will be represented as stress.  Note: However do not think that stress is a force.

17  Also called ELASTICITY OF LENGTH  Describes the stiffness of materials; resistance to compression and tension in one axis Y  High value of Y means high resistance

18 elasticity of shape modulus of rigidity  Also called elasticity of shape or modulus of rigidity S  High value of S means high rigidity

19 elasticity of volume  Also called elasticity of volume compressibility  Its reciprocal is called compressibility K  Higher value of K means the material is harder to compress.

20 SubstanceYoung’s Modulus (GPa) Shear Modulus (GPa) Bulk Modulus (GPa) Aluminum Bone Brass Copper Steel Quartz

21  A wire 2.50 m long has a cross – sectional area of 2.00x10 -3 cm 2. When stretched by a force of 80.0 N it elongates by 5.00x10 -2 cm. Determine › the tensile stress › the tensile strain › the Young’s Modulus of this kind of wire.  If this material has twice the cross-sectional area with the same length, what must be the magnitude of deformation when subjected to the same force?

22  A certain metal can withstand a maximum shear stress of 8.65 GPa. What magnitude of force is required to puncture a hole of 3.00 cm radius on a metal bar that is 4.00 cm thick?

23  How much is the decrease in the volume of 5.00 cubic centimeter of aluminum when submerged in the sea at a depth where the pressure is 2.35 MPa?

24  A vertical steel beam in a building supports a load of 6.00x10 4 N. If the length of the beam is 4.00 m and its cross-sectional area is 8.00x10 -3 m 2, find the distance it is compressed along its length.

25  A solid sphere of volume m 3 is dropped in the ocean to a depth of about 2,000 m where the pressure increases by 2.00x10 7 Pa. Lead has a bulk modulus of 7.70 GPa. What is the change in the volume of the sphere?

26  What magnitude of force is required to puncture a square hole, 3.00 cm on each side, on a steel bar of 5.00 cm thickness? The maximum stress that steel can withstand is approximately 85.0 GPa

27  Prepare for seatwork on Elastic Moduli  Answer the following questions in your LNB. › What is the atmospheric pressure at sea level (standard atmospheric pressure)? › Differentiate gauge pressure and absolute pressure. › State Pascal’s Principle on hydrostatic pressure. › Illustrate and explain Pascal’s Principle using Pascal’s vases and hydraulic press.


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