Young Jeffrey is bored, and decides to throw some things out of the window for fun. But since he is also very curious, he decides to do so in a controlled way. Jeffery takes a rock, his tennis ball, and one of his fathers golf balls and sets them on the sill of an open window. Then he uses a flat board to carefully push them all out of the window at the same time. The 2nd story window is 10.0 ft above the ground, and all three objects hit the ground just 0.500 ft away from the base of the house at the same time, 0.788s after they're dropped. The rock hits with a thud and stays put, but the other two objects bounce. After another 0.591s, the tennis ball reaches a maximum height of 5.63 ft, while the golf ball is 7.88 ft off the ground and still rising. Both have travelled an additional 0.375ft horizontally. Calculate the magnitude of the average velocity of each object during these 1.38 seconds. Which object has the largest instantaneous velocity at the end of this time period?