A small rock is thrown vertically upward with a speed of 17.0m/s from the edge of the roof of a 22.0m 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.

Question

1. what is the speed of the rock just before it hits the street?
2. How long after the rock is thrown will it hit the street?

Answer 1

h(t) = 22.0 + 17.0t - 4.9t^2
v(t) = 17.0 - 9.8t

So, find t when h=0, and use that to find v at that instant.