What initiates the movement of a mass in a mass-spring system?

• A. Elastic restorative force
• B. Sound medium
• C. Displacement force
• D. Sound source

Answer: (C)

The movement of a mass in a mass-spring system is primarily initiated by a displacement force. This force applies when a mass is moved from its equilibrium position, causing the spring to either stretch or compress. Once the mass is displaced, the spring exerts an elastic restorative force that attempts to return the mass to its original equilibrium position.

The displacement force is crucial as it creates the initial movement that sets the system into motion. It can come from different sources, such as an external push or pull applied to the mass, which temporarily alters its position. This interaction between the mass and the spring leads to oscillatory motion once the force is removed and the spring pushes back.

In contrast, the other options do not act as initiators of movement in this context. An elastic restorative force acts after the displacement occurs to restore equilibrium, while a sound medium and sound source are related to wave propagation in acoustics but do not directly influence the initial movement of a mass in a mass-spring system.