A construction worker pulls a five-meter plank up the side of a building under construction

A construction worker pulls a five-meter plank up the side of a building under construction by means of a rope tied to one end of the plank (see figure). Assume the
opposite end of the plank follows a path perpe ndicular to the wall of the building and the worker pulls the rope at a rate of 0.15 meter per second.
How fast is the end of the plank sliding along the ground when it is 2.5 meters from the wall of the building?