An ant runs from an ant-hill in a straight line so that its velocity is inversely proportional to the distance from the centre of the ant-hill. When the ant is at point A at a distance `l_(1) = 1m` from the centre of the ant-hill, its velocity `v_(1) = 2 cm//s`. What time will it take the ant to run from point A to point B which is at a distance `l_(2) = 2m` from the centre of the anthill ?