Physics Material Properties Quiz

Solids and Fluids

• Solids: Atoms in a fixed arrangement, possess definite shape and volume
• Fluids: Atoms are free to move, can flow, and take the shape of their container
• Atoms: Very small, 10⁻¹⁰ m (or 0.1 nm), measured in angstroms (Å)
• Avogadro's number (N_A): 6.022 x 10²³ atoms/mol (atoms in 12g of ¹²C)
• Diamonds: Composed of carbon atoms, density 3.51 g/cm³ (3510 kg/m³)
• Carat: Unit of mass for diamonds (1 carat = 200 mg = 2.00 x 10⁻⁴ kg)
• Nanomaterials: New structures made entirely of carbon atoms
• Fullerenes: 60 carbon atoms arranged in a truncated icosahedron (Buckyballs)
• Carbon nanotubes: Interlocking hexagons of carbon atoms
• Graphene: 2-dimensional sheet of carbon atoms arranged in a hexagonal lattice
• Nanomaterials : Revolutionize material science from Fullerenes, carbon nanotubes, and graphene

Moles

• SI unit for amount of mass is gram-mole (or mole)
• Mass of one mole= atomic mass number in grams
• ¹²C: 12 grams have 6.02 x 10²³ atoms
• ¹⁹⁷Au: 197 grams have 6.02 x 10²³ atoms
• Molecules: Add atomic mass numbers to find relative mass
• Oxygen (O₂): mass number 16; relative mass number 32; 32g = 6.02 x 10²³ molecules
• Atmosphere: Composed of Nitrogen, oxygen, argon, water vapor, traces of CO2

Elasticity of Solids

• Solids: Composed of atoms arranged in a 3D lattice
• Lattice: Atoms have specific distances from neighbors, forces that hold lattice together modeled as springs
• Elasticity: Ability of a solid to deform and return to its original shape when the force is removed
• Elastic limit: The maximum amount of deformation a solid can undergo without becoming permanently deformed
• Types of deformation: Stretching, compression, shear
• Examples of deformations: Power lines stretching, Hoover Dam compression, scissors shearing

Stress and Strain

• Stress: Deforming force per unit area
• Strain: Unit deformation
• Modulus of elasticity: Constant relating stress to strain
• Different moduli for each type of deformation
• Concepts only apply if elastic limit not exceeded

Tension

• Tension: Stretching
• Stress: Force F per unit area A, perpendicular to the area on the end and parallel to the stretching direction
• Young's modulus (Y): Constant in the stress-strain relationship
• Table 13.1: Shows some representative average values for Young's modulus

Compression

• Compression: Volume change
• Stress: Pressure (force per unit area) applied to the entire surface
• Bulk modulus (B): Constant relating pressure to fractional volume change
• Table 13.2: Shows some representative values for bulk modulus

Shear

• Shear: Parallel force to the area, change in shape
• Stress: Force per unit area parallel to the cross-sectional area
• Shear modulus (G): Constant relating stress to strain
• Table 13.3: Shows some representative average values for shear modulus

Wall Mount for Flat-Panel TV

• Shear stress on bolts: Force/Area (calculations provided in text)
• Shear modulus, deflection of bolts (calculations provided in text)

States of Matter

• Gases: Atoms or molecules move freely, compressible
• Liquids: Nearly incompressible, fill corresponding volume in container
• Solids: Definite shape, nearly incompressible;
• Other states: Plasmas, foams, gels, Bose-Einstein condensates, Biological material

Pressure

• Pressure: Force per unit area (measured in Pascals, abbreviated Pa)
• Atmospheric pressure: 1 atm= 1.013 x 10⁵ Pa
• Other non-SI units: Torr, mm Hg, lb/in²

Weighing Earth's Atmosphere

• Composition of Earth's atmosphere: Nitrogen, oxygen, argon, water vapor, CO₂
• CO₂ content varies seasonally, rising since Industrial Rev
• Mass of Earth's atmosphere (calculations provided in text)
• Mass of CO₂ in Earth's atmosphere (calculations provided in text)

Pressure-Depth Relationship

• Pressure increases with depth, follows equation p = p₀ + ρgh

• Pressure on submarine at depth of 250m (calculations provided in text)

Gauge Pressure and Barometers

• Gauge pressure: Difference between absolute pressure and atmospheric pressure
• Barometer: Measures atmospheric pressure; commonly uses mercury or water height

Mercury Barometer

• Mercury barometer: Tube of mercury inverted in a mercury container; height of mercury column is related to atmospheric pressure

Water Barometer

• Height of water column in equivalent water barometer

Manometer

• Manometers: U-shaped tube partially filled with liquid to measure gauge pressure of a gas

Barometric Altitude Relation for Gases

• Relationship between atmospheric pressure and altitude:
  p(h) = poe⁻^hpog/Po

• Calculations for atmospheric pressure at high altitudes.

Air Pressure on Mount Everest

• Calculations for air pressure at summit of Mount Everest (example calculation provided)

How Close?

• Actual data versus formula for atmospheric pressure at various altitudes.

Concept Check Questions

• Several questions on calculating and understanding pressure, solids, fluids and related concepts from different problems.

Pascal's Principle

• Transfer of pressure in incompressible fluids: No losses occur when pressure in an enclosed fluid is changed,
• Application to hydraulic devices
• Calculations to find force on a second piston to a first piston.

Archimedes' Principle

• Buoyant force equals weight of the displaced fluid
• Floating and sinking objects
• Calculations in floating or sinking objects and situations

Floating Iceberg

• Iceberg fraction visible above the water (calculations and explanation provided).