The two springs work together to support the weight of the mass and provide a restoring force when the mass is displaced from its equilibrium position. This allows the mass to oscillate up and down in a harmonic motion.
The stiffness, or spring constant, of the springs determines how much force is required to stretch or compress them. A higher spring constant means the springs are stiffer and will provide a stronger restoring force, resulting in a faster oscillation of the mass.
The equilibrium position is the point where the weight of the mass is balanced by the restoring force of the springs. In this system, the mass will be at rest when it is hanging at the midpoint between the two springs.
The mass affects the natural frequency of the system by changing the overall inertia and the amount of force required to move it. A heavier mass will result in a lower natural frequency, meaning the oscillations will be slower.
Yes, the two springs can be replaced with a single spring, as long as the spring constant is equivalent to the combined spring constants of the two original springs. This single spring will act as a virtual spring, with the same effect on the system as the two separate springs.