A construction worker pulls a ve-meter plank up the side of a building under construction by means of a rope tied to one end of the plank (see gure). Assume the opposite end of the plank follows a path perpendicular to the wall of the building and the worker pulls the rope at a rate of 0.21 meter per second. How fast is the end of the plank sliding along the ground when it is 1.2 meters from the wall of the building? (Round your answer to two decimal places.) 1 5m m/sec