In animated modes, this determines how quickly the particle emission position moves around the arc.
The value is specified in terms of the number of complete 360 degree rotations. A value of 2 would mean that the particle emission position rotated 2 full times per second. Additional resources: ParticleSystem.ShapeModule.arcMode, ParticleSystemShapeMultiModeValue, ParticleSystem.ShapeModule.shapeType.