I am just learining basic dynamics from spring mass system. there is a horizontal spring fixed to the wall and a mass is at the end. When the mass is displaced by a force F to the right the spring stretches to a distance X. Now i draw the STATIC FBD. The eqn is f-kx=net force on the mass. Now i draw the kinetic diagram and the equation i derive is f-kx=ma where a is the acceleration of the mass m. So for this spring mass system the dynamic equation is f-kx-ma=0. Is what i have done is true and correct?