I posted a new revision of rotation, and I had some questions:

http://www.colorado.edu/physics/phet/dev/rotation/0.00.16/

Can you look at this version and comment on whether the mechanics look correct? In particular, there are 2 modes of operation:

on platform:

- the character is on the platform and the user is manipulating the platform (either by setting its angle, angular velocity or angular acceleration)

off platform:

-the character is being manipulated directly by the user

I’d like to know if you think the velocity and acceleration vectors look correct and smooth enough for these (4) modes of behavior. The acceleration is very jittery in the case of “off platform”; do we want to smooth this for example for the instance in which the user drags the character in a circle?

A small amount of feedback on this will be very helpful in getting ready for AAPT; also, we should meet together soon to discuss issues with respect to multiple series on one chart and charting multiple objects.

Here are my responses to your questions. 

(1) Maybe for this problem, we could have checkboxes for each variable that appears when you have a certain button selected under the "Show graphs for:" section.  There seems to be a little extra room, here, am I right?  Maybe when you select which graphs to show, a list of variables would come up with a checkbox next to each so the user could select which variables to show.  Since these options would appear only when a selection is made, it might make it more obvious that they even have a choice?

(2) The only solution I can think of off the top of my head would be that maybe there is some way to show that one of the characters is "selected" and then either have only the graphs for that character shown, or have the lines for that character be more bold and the lines for the "unselected" character be slightly faded, and then also have a feature where you can hide some of the lines.  Although it seems like this could all get very confusing with so many data series for each graph.

(3) I can't remember which other names we came up with.

(4)  I would think that we would want to show these values for the characters, and not just for the merry go round, because we want to be able to show that as the characters move to different places on the merry go round, the values for their angular position, velocity, and acceleration don't change.  But it still may be useful to have an option to show the values for just the merry go round.

(5) I can't remember why exactly we discussed having the side view option.  It seems like this may be a little confusing at times, because all they will see is just the characters moving from side to side.  I would think that to eliminate some of this confusion, you would want to somehow show both the top view and the side view at the same time.  So I like the idea of having the x- and y-projections shown, however, I am not sure if using the words "x- and y-projection" would be understood by all.  But then again, I can't be sure that people would really be confused about this or by the side view until doing interviews on it.  I do like the way that the rotation is done in Wave interference, where you actually show the rotation, and I think that if people are confused this could help eliminate some of the confusion. 
Other comments:
1.  When I open the version you sent on my computer, the characters start out so far in the upper left side of the screen that I almost can't see them, and it's hard to grab them. 

I think it would be a great idea to meet and talk about this stuff sometime, because we haven't really had much discussion of it for several months, and it would be much easier to discuss in person.  Kathy is out of town for the rest of the week, though, so perhaps we should wait until she returns?

Mindy

Samuel Robert Reid wrote:

Kathy, Wendy, Mindy,

I’m ready for feedback on the rotational motion simulation; I’m happy to meet at your office for a brief discussion of these issues if you like.  Below is a summary of my two previous emails in this thread, and here is a version with two characters (in the top left corner of the play area):

http://www.colorado.edu/physics/phet/dev/rotation/0.00.14/

My main questions for now focus on the graphs: which graphs should be shown, and how should different graphs be consolidated?  Specifically:

For the linear variables, (position, velocity, acceleration), do we wish to show x-component, y-component and magnitude?  If so, there should be a way to disable different series (otherwise graphs are quite cluttered).  Where should the enable/disable functionality be?  Perhaps a checkbox next to the variable name?

For showing variables attached to two different bodies, should they both appear on the same graph?  If so, how should they be differentiated (by Color, stroke, etc)?  Also, showing the x-component, y-component and magnitude for two characters on the same graph (6 series data) might be a bit crowded.  If we allow this, we should have a way to disable certain series.  Perhaps they should use the same graph, but show/hide depending on whether the character is placed on the merry-go-round.

Three proposed names for this simulation were “rotational motion”, “merry-go-round” and “mary-go-round”, but I recall that at a subsequent phet meeting, another name was proposed that was much more appealing than these three, but I don’t have any documentation about what it was (and I think it was before Sam M started taking minutes).  Can anyone recall this name?

Currently the angular graphs (angle, angular velocity, angular acceleration) are reading out values from the merry-go-round platform.  Should I switch this to readout values for the characters?  Should those readouts be on the same graph?  Should we still support graphs for the merry-go-round, or characters only?  If we do both, should they appear on the same graph?

How should the side-view look?  Would you like a quasi-3d continuous rotation (as in the waveinterference simulation), or just a toggle which puts up the side view?  (The specs indicate a toggle, but I thought I’d double-check.)  Also, what do you think about putting x and y projections to top and side of the merry-go-round?  Perhaps this would be easier, since it would allow us to sidestep questions about what happens if you try to drag a character while in “side view”, and it would allow you to view both representations at once.  On the other hand, “side view” may be easier to relate to than x and y projections (unless we use shadows or equivalent).