Consider a block of mass m connected to a horizontal spring, placed over a frictionless surface. The net force on the block is the sum of the force due to its weight, the normal force, and the force due to the spring. Since the weight and the normal force are of equal magnitude and opposite in direction, they cancel each other, and the net force becomes equal to the force due to the spring. Here, the magnitude of force is proportional to the first power of displacement. Because of this, the spring-mass system is called a linear simple harmonic oscillator. Using Newton's second law, the force can be expressed in terms of acceleration. Substituting the expressions for acceleration and displacement, the equation for angular frequency is obtained. The angular frequency is also defined as 2π over the period of oscillation. Also, the inverse of the period is the frequency of oscillation. A stiff spring produces rapid oscillations and a short period. In comparison, a heavy object tends to produce sluggish oscillations and a large period.