Posted by Kristen on .
A hoodlum throws a stone vetically downward with an initial speed of 12.2 m/s from the roof of a building, 28 m about the ground. How long does it take the stone to reach the ground? What is the speed of the stone at impact?

Physics 
bobpursley,
hf=hi+ Vo*t + gt
solve for t Watch coordinate system...