PhET - Default Damping Value?

[jalex003]

Homework Statement

I have been tasked to investigate the default settings on the Colorado PhET for "Masses and Springs" - which helps students understand Hooke's Law. More specifically - I want to know what the default damping value is set to in this simulation (as indicated in the photo attached).

Relevant Equations

The damping force is proportional to the velocity (F = -c * v ), and the damping slider controls c.

PhET: https://phet.colorado.edu/en/simulation/masses-and-springs

Any information would be appreciated.

Thanks in advance!

 

[berkeman]

Welcome to the PF.

It seems like starting with very little damping is a good thing to do, since it helps the student to see how the oscillation works when it is unhindered. Then turning up the damping is instructive to show underdamped, critically damped, and overdamped behaviors. Have you gone through those 3 cases of damping yet?

 

[jalex003]

Hi berkeman,

Thank you for the welcome to this community.

I have gone through those 3 cases of damping as you have described. I'm just curious as to why whenever I restart this particular PhET, I notice that the damping level adjusts to a pre-programmed value (that is in between "none" and "lots" <? units>). Essentially, I'm not sure whether or not this is arbitrary - or a pre-defined constant...

The teaching guide for "Masses and Springs" mentions damping briefly and cites their Github model. But I haven't found a satisfactory resolution as to what the default setting for damping means in the lab component of the simulation...

 

[berkeman]

I'm not able to tell from a quick look, but do they show the full equation of motion with the various terms defined?

http://hyperphysics.phy-astr.gsu.edu/hbase/oscda.html

 

[jalex003]

Thank you for providing me with the hyperphysics link! This is a good resource to have as a bookmark...

I'm still scratching my head over why did the app designers choose this specific damping coefficient? Is it relevant to real life in some way?

 

[berkeman]

So when you start the app, does it show an undamped oscillation that just keeps going? That's probably a good starting point for students to get to see what happens with a mass on a spring.