dF/dD represents the derivative of F(D), which measures how quickly F changes with respect to D. It gives us information about the rate at which fuel decreases as distance increases.
Related terms
Derivative: The derivative measures how much a function changes when its input variable changes.
Rate of Change: Rate of change describes how much one quantity changes with respect to another quantity.
Implicit Differentiation: Implicit differentiation allows us to find derivatives when we have an equation involving both dependent and independent variables.