Since the first derivative of a function represents the rate of change of the function y=f(x) with respect to x, the second derivative represents the rate of change of the function. For example, in ki...Since the first derivative of a function represents the rate of change of the function y=f(x) with respect to x, the second derivative represents the rate of change of the function. For example, in kinematics (the study of motion), the speed of an object (y′) signifies the change of position with respect to time but acceleration (y′′) signifies the rate of change of the speed with respect to time.