posted by NINI .
Frank stands at the base of a building. He throws a 0.12kg rock straight up at a speed of 28m/s so that it rises to a maximum height of 12m above the top of the building and then falls straight down on the roof of the building.
a) What is the height of the building?
b) What is the velocity of the rock just before it lands on the roof?
At the very top of the flight, velocity is zero.
t= vi/4.2 Now put that time in
Then, find vf when h=heightbuilding