3. Fundamentals of Process Geomorphology The Basics of Modern Geomorphology Dimensions and Units –Rules –System of units Fundamentals of Physical Equations

The Basics of Modern Geomorphology Process: Action produced when a force induces a change in the materials or forms at the Earth’s surface Force:….anything that changes or tends to change the state of motion of a body (standard units for force are Newton or Dynes) (standard units for force are Newton or Dynes)

Interesting quotation (from Ritter, 1995, Process Geomorphology, p. 11). “We suggest that geomorphology can be examined by using physical concepts that resolve around the application of forces on surface materials….The effect of processes depends on how vigorously the forces drive then and how strongly their action is resisted by the geological framework”.

Rules to manipulate dimensional quantities:

Units… SI units (System international SI units) –mass (kg), force (N), length (m), time (s) Centimeter-gram-second (cgs) units English units (pounds, feet…) Dimensional character of each quantity expressed as: M a L b T c

Types of equations Equations of definition Conservation equations –Mass, energy, momentum Equations of motion (fluxes) Force-balance equations Empirical equations

Foundations of physics:

Potential and kinetic energy… Potential energy: –The potential energy (E p ) of a body results from its position relative to some reference level – E p = mgz where: m is mass, g is acceleration due to gravity, and z elevation above a reference level (e.g. ground surface, sea level….) where: m is mass, g is acceleration due to gravity, and z elevation above a reference level (e.g. ground surface, sea level….)

Kinetic energy…. In contrast, the kinetic energy (E v ) of a body results from its motion. E v = 0.5 m V 2 (where V is velocity and m is mass).

Definitions… Dynamics: The study of forces on, and acceleration of moving bodies Kinematics: The branch of mechanics dealing with the description of the motion of bodies (without reference to the force producing the motion) Fluid mechanics: study of motion of fluids and conditions governing that motion (mechanics generally includes kinematics and dynamics) (mechanics generally includes kinematics and dynamics)