def act(environment)
    environment.objects.each do |object|
      object.vector.speed = Utility.constrain_value(object.vector.speed, @maximum)
    end
  end
def act(environment)
    environment.objects.each do |object|
      object.vector.speed = Utility.constrain_value(object.vector.speed, @maximum)
    end
  end
If object is over the speed, reduce its speed.