*They say that the mechanical analogues of capacitors are springs, and*

>of inductors are shock absorbers.

>of inductors are shock absorbers.

Like shock absorbers, both capacitors and inductors can absorb "shock" (see

power supplies) and

like springs, both can store energy for later release (see resonant

circuits) .

In lay terms -

There are several elements in linear mechanical systems:

-mass (qty of "material"),

-spring (converts kinetic to potential), -damping (converts kinetic to heat and

deducts it from the mechanical sum),

-kinetic energy (energy from motion), and -potential energy (energy from

position).

There are several analogous elements in electromagnetics:

-charge (qty of "material"),

-capacitor and inductor, (converts kinetic to potential),

-resistor (converts kinetic to heat and deducts that energy from the electrical

sum)

-current (energy from motion of charge),

and

-voltage (defined as the potential energy between two positions in a field)

*But do springs/shock absorbers have any kind of frequency-dependent >behaviors?*

However, there are phenomena associated with springs and shocks that can

affect natural frequency over time. One classic is the automobile front

suspension, where loss of spring constant from fabrication-stress relaxation in

the coils (about 40% loss over two years) causes less-tight-handling, which can

be compensated back to near original by using a larger than original damping

constant (heavy duty shock).

(You can work it out from the equation fx^2 + cx + d, and there are a couple

of papers from the 70s on it if you are not familiar with frequency equations)

In the real world, as the frequency increases, the mass of the spring itself

enters into the system as a separate equation and creates tertiary resonance as

well as effecting the original theoretical spring-mass assumptions (f=ma).

There are a couple of charts I have seen listing corresponding elements for

linear mechancial, rotary mechanical, fluid power, air power, and

electromagnetic/electrical, and their equations.

Control engineers find them fairly useful.

hope it helps