posted by joe .
A small rock is thrown vertically upward with a speed of 13.0from the edge of the roof of a 37.0 tall building. The rock doesn't hit the building on its way back down and lands in the street below. Air resistance can be neglected.
A) What is the speed of the rock just before it hits the street?
Total energy at start = (1/2) m Vi^2 + m g h
Total energy at finish = (1/2) m v^2
no losses so
(1/2) m v^2 = (1/2) m (13)^2 + m g (37)
v^2 = 169 + 2(9.81)(37)