This model illustrates the concept of forced oscillations of a weight on a spring. Harmonically changing external force is applied to the free end of the spring. It makes the end oscillate under the law y = y_{m}cosωt, where y_{m} is the amplitude of the oscillations and ω is the angular frequency. Press ?Run?, and observe how the external forces impact the oscillating system. In addition to demonstrating the functioning of stationary forced oscillations, the model also demonstrates how the stationary forced oscillations settle (transient process). It is possible to change the mass of the weight m, the spring?s elastic constant k, and the factor of viscous friction b. Observe the time dependency graphs of the coordinate and of the velocity of the body, as well as other parameters of the oscillations that are shown on the graph. Study the resonance curve. Note that stationary forced oscillations always occur at the frequency of the driving force. The resonance occurs when this frequency approaches the fundamental frequency of the oscillating system.