PhET Progress Report

Sam Reid

March 1, 2007


An online version of this report is available here.

Here’s a pie chart representation of the time distribution.


Energy Skate Park

  • About 3 hours of work this week.
  • Added collisions with spline
    • Sometimes ball falls through spline (multiple collisions missed?)
  • Added sticking to spline
  • Still not a fine estimate of total work required, ballpark estimates:
    • 5 hours: finish curvature computation for leaving track
    • 5 hours: add multiple splines
    • 15-20 hours: add mathematics & implementation to account for center-of-mass offset
    • 6 hours: spatial extent for particle
    • 8 hours: validation and effort to ensure energy is conserved
    • 8 hours: integrate with energy skate park
    • 10 hours: issues that should be on this list that I don’t know about right now
    • 10 hours: miscellaneous issues/bugs that arise
  • This adds up to 72 more hours (with a great deal of uncertainty)
    • already worked 18 hours on it, including some time with Dubson
  • Issues
    • What about the possibility of putting the center of mass directly on the track?
    • This time estimate is significantly larger than previous speculation.  We should decide how much this rewrite is worth to us.



  • Discussions of repository architecture
  • Large-scale restructuring of repository
  • Testing new repository


Repository Migration

  • Collaborated with John
  • Postponed due to a Sourceforge service outage.
    • Sourceforge said it should have been back by Feb 21, but today (Feb 22) status is still listed as “Unscheduled Outage”
  •  Process is more or less automated
  • We’ll try again Feb 24



  • Assist with repository conversion
  • Sourceforge issues
    • update notification hooks
  • Testing


Phet Project

  • Investigate techniques for sharing project files
  • Start template for large phet project
    • About 7 simulations so far


Upcoming Work

  1. Energy Skate Park

a.       Collaborate with Dubson to improve physical model

b.      Evaluate new physical model before working on any physics-related bugs.

c.       Track should bump up when beneath ground

  1. Collaborate with De Goes to improve simulation build process & isolate dependencies.
  2. Rotational Motion Simulation I

a.       Time series/playback

b.      Lots of minor user interface updates

c.       Performance enhancement

  1. Rotational Motion Simulation II
  2. CCK…