Springs

To solve this question, we need to understand the analogy between mechanical and electrical systems. The analogy helps us match quantities from one system to those in another system. Let's explore how these quantities relate:

1. Mass (P) vs. Inductance (5): In electromechanical analogies, mass in a mechanical system is analogous to inductance in an electrical system. Both store energy in kinetic and magnetic fields, respectively.
2. Spring Constant (Q) vs. Reciprocal Capacitance (3): The spring constant, which dictates the stiffness of a spring, relates to the reciprocal of capacitance. This is because both depict the idea of how systems store potential energy: elastic potential energy in a spring and electric potential energy in a capacitor.
3. Displacement (R) vs. Voltage (2): Displacement in a mechanical system is analogous to voltage in an electrical system. Displacement measures how far a point in a mechanical system moves, while voltage measures the potential difference in an electrical system.
4. Velocity (S) vs. Current (1): In mechanical systems, velocity describes the rate of change of displacement, while in electrical systems, current describes the rate of change of charge. Thus, they are analogous.

Based on the above analogies, the correct matching is:

The correct answer is therefore: P-5, Q-3, R-2, S-1.

This understanding helps in the interpretation and translation of principles from one type of physical system to another, aiding in applications like system modeling and control systems.