% 	car_drag.m
%	This function, which is called by the program 'car2.m', contains the 
%	equation of motion of a car on an incline subjected to form drag. It
%   is assumed that the car velocity is nonnegative.
%
% 	Introduce  V_dot, the time derivative of v.
%
function V_dot = car_drag(t,v)
%
%	Declare global parameters (a MATLAB detail).
%
global g alpha ACd m 
%
%	The mathematical model of the car provides an equation for v_dot.
%
V_dot = g * sin(alpha * pi/180) - (ACd/m) * v^2;
%
%	That's all there is to it!
