Attach to track if velocity is close enough to parallel to the track
Estimate u dot from equations (8) & (9) in the paper
renamed function
use skater value for gravity
When falling straight down, stop completely and convert all energy to thermal
added todo
Keep angle when leaving a track, but optimize for straight up and down skater
When the bar graph is shown, update the bars (because they do not get updated when invisible for performance reasons)
Specify movable dialogs as pickable:true