Simple Harmonic Motion and Damping

[SnackMan78]

Textbook Question:

Which one of the following terms is used to describe a system in which the degree of damping is just enough to stop the system from oscillating?

a) Slightly damped
b) Underdamped
c) Critically damped
d) Overdamped
e) Resonance

Textbook says that the smallest degree of damping that completely eliminates the oscillation is termed "critical damping". (This example has no picture to illustrate it.) Then a couple of lines later in the textbook, "Typical automobile shock absorbers are designed to produced underdamped motion somewhat like that in curve 3. (an illustration that highlights the best scenario of the motions: underdamped and undamped motion)

My answer is C based on the first textbook example, but I want to get confirmation from others. The shock absorber and underdamped line of text is somewhat confusing. Any other thoughts?

 

[Hootenanny]

(c) is correct. Critical damping occurs when the resistive forces are 'just enough' to prevent an ocsillation as you say. Most motor car shock absorbers are made slightly underdamped, this still gives a good ride without too much 'boucing' but also gives the car quicker responses.

-Hoot

 

[FredGarvin]

You should realize that to physically make something critically damped is impossible. It aint going to happen. That then leaves the option of over or underdamping. Over damping would cause a pretty rough ride. It would be pretty rigid. If it is underdamped, that allows an oscillation, but results in a softer ride. The idea is to not be too much underdamped.

You are corrct with C as Hoot has said.