4.A rock is thrown vertically upward with a spced of 13.0 m/s from the roof of a building that is 60.0 m above the ground.On the way down the rock barely misses the edge of the building and continues to fall to the ground.Ignore air resistance.
a5 points How long does it take for the rock to strike the ground?
(b) 5 points) How fast is the rock going when it strikes the ground