A rock is thrown from the edge of the top of a 100-ft tall building at some unknown angle above the horizontal. The rock strikes the ground a horizontal distance of 160 ft from the base of the building 5.0 s after being thrown. Assume that the ground is level and that the side of the building is vertical. Determine the speed with which the rock was thrown.
1) 72 ft/s
2) 77 ft/s
3) 68 ft/s
4) 82 ft/s
5) 87 ft/s
Answer: 3