"Number of mass" seems to actually be the "number of masses per row". Confirm and rename these things:
In NormalModesConstants:
NUMBER_OF_MASSES_RANGE: NUMBER_OF_MASSES_RANGE, //TODO actually number of masses PER ROW
In NormalModesModel:
// @public {Property.<number>} the current number of visible masses
//TODO this is actually the number of masses per row. In the 'Two Dimensions' screen, the number of masses is this value squared. https://github.com/phetsims/tasks/issues/1129
this.numberOfMassesProperty = new NumberProperty( options.numberOfMasses, {
"Number of mass" seems to actually be the "number of masses per row". Confirm and rename these things:
In NormalModesConstants:
In NormalModesModel: