. Bug: When user drags track that skater is resting on, the skater doesn't move with it. . Bug: The ground can't be driven on (only bounced off). . Make object mass switchable. . Change skaters/vehicles graphics. . Add game-ish modes to sk8r application . 2-skater mode . Grab the apple? . Figure out the meaning of the magic grab number in EnergyConservationModel . Fix Minor bug (but one which prevents foreign launch) of Schrodinger. . Repaint bug in Conductivity