The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector. That is Newtons 2nd law of motion, broken down, means mass i.e. the small vs. large car and force i.e. moving. Your answer is second law of motion.
