The BottomParamB property is relevant when a part’s
/BasePart/BottomSurface is set to Motor or SteppingMotor and
/BasePart/BottomSurfaceInput is set to Constant or Sin. For Constant, it determines the constant rotational velocity of the motor. For Sin, it determines the frequency of the motor’s rotational velocity, using the following formula:
MotorVelocity = ParamB * math.sin(workspace.DistributedGameTime * ParamB)
In no other cases is this property used.
This code sample demonstrates how surface properties can be set using only a NormalId (Top, Front, etc). It switches a motor’s -SurfaceInput from NoInput, Constant and Sin to show how each work using -ParamA and -ParamB properties.