Not all periodic motions are classified as simple harmonic motion, as many periodic motions, like a swinging pendulum or the Earth's orbit around the sun, do not fit this definition. Simple harmonic motion is characterized by a single frequency, represented mathematically as x1(t)=Asin(ωt). When combining two harmonics, such as x(t)=x1(t)+x2(t)=Asin(ωt)+Asin(2ωt), the resulting motion's period and graph can be analyzed for further understanding. A periodic function is defined as one that repeats itself after a constant interval T, satisfying the condition f(t)=f(t+T) for all t. Understanding these distinctions is crucial for grasping the principles of periodic motion.