Comparative Biomechanics: Life's Physical World - Vocabulary Flashcards

fifty vocabulary flashcards covering key terms and definitions from the lecture notes on biomechanics, scaling, and physical principles in biology.

Biometrics or Biomechanics

The study of mechanical principles applied to living systems, integrating physical, mathematical, and biological perspectives.

Comparative biomechanics

A field examining how the design and function of organisms vary across species, habitats, and evolutionary histories.

Human/biomedical biomechanics

Biomechanics focused on humans and medical applications, including prosthetics, locomotion, and rehabilitation.

Conservation of mass

Mass remains constant in a closed system; in fluids, the flow rate is constant (continuity principle).

Incompressible fluid

A fluid whose density is effectively constant, so mass flow equals volume flow through a conduit.

Cardiac output

The volume of blood pumped by the heart per unit time.

Capillaries

Tiny blood vessels where blood flow slows and exchange with tissues occurs.

Momentum

The product of mass and velocity; a vector quantity that is conserved in isolated systems.

Impulse

The integral of force over time; the change in momentum during a force interaction.

Conservation of momentum

Total momentum is constant in the absence of external forces.

Conservation of energy

Energy cannot be created or destroyed in an isolated system; it can be transformed.

Laplace's Law

Relation between pressure, tension, and curvature: Δp = T/r for a cylinder; Δp = 2T/r for a sphere.

Hoop stress

Circumferential tensile stress in the wall of a cylinder (σh ≈ Δp r/Δr for thin walls).

Longitudinal stress

Stress along the length of a cylinder (σl ≈ Δp r/(2Δr)).

Tensile stress

Stress caused by pulling forces per unit cross-sectional area.

Compressive stress

Stress caused by pushing forces per unit cross-sectional area.

Shear stress

Stress from parallel forces on a surface, causing deformation by shear.

Radius of curvature

Radius of the curved surface (cylinder or sphere) relating pressure to wall tension.

Wall thickness

Thickness of a wall; affects how pressure translates into wall stress.

Center of gravity

The point where the total weight can be considered to act; axis for balance.

First moment of area

Integral of area elements times their distance from a pivot; relates to leverage.

Second moment of area

Integral of area elements times the square of their distance from a pivot; relates to bending stiffness.

Moment of inertia

Second moment of area for rotating bodies; measures resistance to angular acceleration.

Surface-to-volume ratio

Ratio of surface area to volume; changes with size and affects exchange processes.

Shape factor

A size-normalized descriptor of shape influencing physical behavior.

Vogel number

A dimensionless shape index defined as S^(1/2)/V^(1/3) to compare shapes independent of size.

Dimensional analysis

A method for deriving relationships by ensuring dimensional consistency in equations.

Dimensional homogeneity

Requirement that every term in an equation has the same physical dimensions.

Dimensionless numbers

Pure, unitless ratios that summarize relationships (e.g., Reynolds, Bond numbers).

Drag coefficient

A dimensionless factor Cd that quantifies drag relative to a reference force (Fd/0.5ρv^2A).

Bond number

Ratio of body forces to surface tension; Bo ≈ ρgL^2/γ (order of magnitude).

No-slip condition

Fluid velocity at a solid boundary equals the boundary velocity, creating a velocity gradient near the surface.

Gradient

A rate of change of a quantity with respect to space or time (e.g., temperature, concentration, velocity).

Thermal gradient

Spatial rate of temperature change driving heat transfer.

Temperature gradient

Spatial gradient of temperature within a material.

Concentration gradient

Spatial change in concentration driving diffusion.

Velocity gradient

Rate of change of fluid velocity with distance, creating shear in flows.

Diffusion

Spread of a substance from regions of high to low concentration.

Fick's law

Diffusion flux is proportional to the concentration gradient.

Fourier's law

Heat flow is proportional to the temperature gradient.

Surfactant

Wetting agent that lowers surface tension, aiding uniform expansion (e.g., alveoli).

Work of extension

Energy stored when a material is stretched; area under a force-extension curve.

Work to fracture

Energy required to fracture a material; area under a stress-strain curve.

Elastic modulus

A measure of material stiffness; ratio of stress to strain.

Stress-strain curve

Plot of stress versus strain revealing strength, extensibility, and stiffness.

Ponderal index

Body-build index: m/(height)^3 (or related forms) used to assess body composition.

Body Mass Index (BMI)

Mass divided by height squared (kg/m^2); used to classify weight status.

Fulton’s condition factor

CF = 100m/L^3; an index used in ichthyology to gauge condition independent of size.

Rohrer index

Mass divided by height cubed (gram per cubic centimeter) for body build assessment.

Rohrer body-build index

A historical mass-to-height index used in anthropometry (similar purpose to BMI).

Center of gravity test

A practical method (e.g., hanging) to locate the center of gravity by balance orientation.