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🔋college physics i – introduction review

Driving Force

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

The driving force is the external influence or stimulus that causes a system to undergo oscillations or vibrations. It is the primary factor that drives the motion or behavior of a system, particularly in the context of forced oscillations and resonance.

5 Must Know Facts For Your Next Test

  1. The driving force must be applied at the natural frequency of the system to achieve resonance, resulting in the largest possible amplitude of oscillation.
  2. The amplitude of the forced oscillations is directly proportional to the magnitude of the driving force, with larger driving forces leading to larger amplitudes.
  3. The phase difference between the driving force and the resulting oscillations depends on the frequency of the driving force relative to the natural frequency of the system.
  4. The energy input from the driving force must be equal to the energy dissipated by the system's damping mechanisms for the system to maintain a steady-state oscillation.
  5. The driving force can be a periodic function, such as a sinusoidal or square wave, or it can be a non-periodic, transient force, such as an impulse or a step function.

Review Questions

  • Explain how the driving force influences the amplitude of forced oscillations in a system.
    • The amplitude of the forced oscillations is directly proportional to the magnitude of the driving force. Larger driving forces will result in larger amplitudes of oscillation, as the system is subjected to a greater external influence that causes it to vibrate with greater intensity. The driving force provides the energy input required to overcome the system's damping and maintain the oscillations at a particular amplitude.
  • Describe the relationship between the driving force frequency and the natural frequency of a system in the context of resonance.
    • For a system to experience resonance, the driving force must be applied at the natural frequency of the system. When the driving force frequency matches the system's natural frequency, the system will oscillate with the largest possible amplitude. This is because the driving force is in sync with the system's natural tendency to vibrate, allowing the energy input to be maximized and the oscillations to build up to a resonant state.
  • Analyze the role of the driving force in maintaining steady-state forced oscillations in a system.
    • For a system to maintain steady-state forced oscillations, the energy input from the driving force must be equal to the energy dissipated by the system's damping mechanisms. The driving force provides the necessary energy to overcome the system's inherent resistance and sustain the oscillations at a constant amplitude. If the driving force is insufficient or if the damping is too high, the oscillations will eventually decay, and the system will not be able to maintain a stable, steady-state response.