Physics of Matters Notes

University:
California State University, Northridge
Course:
PHYS 100A | General Physics I
Academic year:

2023
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0

Pages:

1
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PHYSICS OF MATTERS DEFINITIONS Stress (σ) ratio of perpendicular force, F, to the cross-sectional area, A: σ = F/A unit: Pa (Pascal) or N/m² Strain (ε) ratio of elongation, ΔL, to original length, L₀: ε = ΔL/L₀ no unit Young's Modulus (Y) ratio of the tensile stress to the tensile strain if the proportionality limit has not been exceeded. Y = σ/ε = F/A / ΔL/L₀ = FL₀/AΔL unit: Pa (Pascal) or N/m² Temperature (T) a fundamental quantity that measures the degree of hotness of a body. units: °C, °F, K Heat (Q) energy that is transferred from one body to another because of a difference in temperature. unit: J (Joule) Thermal Equilibrium the state in which the temperature of two bodies are equal when no net energy exchange temperatures are identical Heat Conduction a process where heat is transferred through a solid from a region of high temperature to a region of lower temperature. Thermal Expansion change in dimensions of a body accompanying a change in temperature. Rate of Heat Flow (Q/Δt) Q/Δt = kAΔT/L Thermal Conductivity, k: (high k = good conductor) unit: W/mK or J/s.m.°C Strain Energy Force * Strain = F * ε = F (ΔL/L₀) = FΔL/L₀ Stress (σ) Strain Energy Volume Strain Energy per unit volume Strain (ε) Take note! when in steady state, rates of heat transfer through both materials are the same. ensure (L) is converted to (m³) Example: 2.00 L = 2.00 x 10⁻³ m³ Linear expansion ΔL = αL₀ΔT or L = L₀(1 + αΔT) if given d, then d = L₀αΔT Area expansion ΔA = βA₀ΔT or A = A₀(1 + βΔT) Volume expansion ΔV = γV₀ΔT or V = V₀(1 + γΔT)