Basic Thermodynamics ~ J. Pohl © www.THERMOspokenhere.com (38-A413)

1.17 Value, Slope and Curvature

Science attempts to describe changes of physical reality. The items that change are called properties. Properties are realized to change in time or space. Consider a hypothetical property notated as, F, which changes only as does time. That property is written symbolically as: F(t). For us, any observation of some F(t) over time must begin at (the beginning of its observation) x = x*:

A basic idea of calculus is that a function, F(t), has three characteristics at any specified value of t, say x = x*.  Associated with x* the function has a a value, a slope and curvature. These ideas are illustrated in the sketches below.