7Matter Anything that occupies space and has mass. VolumeMassDensityExhibits gravitational attractionHas inertia
8States/Phases of Matter SolidLiquidGasPlasmaSupersolidsSuperfluids
9Some properties of solids ElasticityMalleabilityDuctilityPlasticityStrengthHardnessFlexibility
10Elasticity vs. Plasticity Elastic and plastic materials are both deformed when subjected to forceDifference:Elastic: material returns to its original dimension when force is removedPlastic: deformation is permanentElastic materials may exhibit plasticity.When and how?
11Malleability vs. Ductility Both are determined by the crystal lattice of the metal, and the strength of the bond between molecules of the metalCopper is malleable and ductile. Aluminum is malleable but not as ductile as copper.
12Hardness vs. StrengthIn the general use, they are the same; the ability o a material to resist deformationConcrete is hard but it may not be as strong as metal.Hardness … deformation due to compressionStrength … deformation due to tension
13Hooke’s Law Also known as Law of Elasticity Robert Hooke For relatively small deformations, the magnitude of deformation is directly proportional to the deforming force.
14Limitations Conditions that fall under Hooke’s Law Relatively small deformationDeformation is within the elastic limitThe material returns to its original dimension when the force is removed
15Illustration for Hooke’s Law Greater deformation requires greater force.The ratio of these too defines the elasticity of the material
16Deformation Quantified 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.
17Young’s Modulus of Elasticity Also called ELASTICITY OF LENGTHDescribes the stiffness of materials; resistance to compression and tension in one axisHigh value of Y means high resistance
18Shear Modulus of Elasticity Also called elasticity of shape or modulus of rigidityHigh value of S means high rigidity
19Bulk Modulus of Elasticity Also called elasticity of volumeIts reciprocal is called compressibilityHigher value of K means the material is harder to compress.
20Typical Values for Elastic Moduli SubstanceYoung’s Modulus(GPa)Shear ModulusBulk ModulusAluminum70.025.0Bone18.080.0-Brass91.035.061.0Copper11042.0140Steel20084.0160Quartz56.026.027.0
21ExercisesA wire 2.50 m long has a cross – sectional area of 2.00x10-3 cm2. When stretched by a force of 80.0 N it elongates by 5.00x10-2 cm. Determinethe tensile stressthe tensile strainthe 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?
22ExercisesA 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?
23ExercisesHow 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?
24SeatworkA vertical steel beam in a building supports a load of 6.00x104 N. If the length of the beam is 4.00 m and its cross-sectional area is 8.00x10-3 m2, find the distance it is compressed along its length.
25SeatworkA solid sphere of volume m3 is dropped in the ocean to a depth of about 2,000 m where the pressure increases by 2.00x107 Pa. Lead has a bulk modulus of 7.70 GPa. What is the change in the volume of the sphere?
26SeatworkWhat 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
27Assignment 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.