A rock is thrown vertically upward with a speed of 27.0 m/s from the roof of a 31.0-m-tall building. The rock doesn't hit the building on its way back down and lands in the street below. (a) What is the speed of the rock just before it hits the street? (b) How much time elapses from when the rock is thrown until it hits the street?

Use the kinematic equation to find the final velocity (v) just before the rock hits the street: v² = v₀² + 2g(h + d), where d is the distance the rock travels above the building. Since the rock is thrown upwards, it will first rise to a maximum height before falling down. Calculate the maximum height using v = 0 at the peak: 0 = v₀² - 2gh₁, solve for h₁.