The Duchess has set up a pendulum in the door to her house by tying a string of 1.5 meter length to a ball of mass 0.9 kilogram and attaching it to the top of the door. Alice notices it is swinging to-and-fro rising to a height of 0.5 meter (from the bottom of its arc) at each end of its swing. As she watches, the Frog-Footman suddenly places a rod 0.8 meter from the top directly under the attachment point. Find how high does the ball now rise on the side with the rod?