Hello, I have to write a fortran program to computer the flight traj of a projectile. I am given dt, initial velocity, angle of departure, initial height, and gravity. I am also given the aerodynamic drag factor (A) values. I have been given the equations, but I am confused as to what the letters stand for. A = k/m dVx/dt = -AVNx dVy/dt = -g - AVNy Fd = kN^2 I have other eqns, but my main question is .. what is the N referring to? The normal? Wouldn't Nx = mass * accel in x direction? and Ny = mass * accel in y dir ? I am not given the mass, though. And what is k in A = k/m (where A = aero drag factor) ? Thanks!