A boy stands on the roof of a 50m tall building and thrown a ball horizontslly at 20m/s away from the building.

How far away from the foot of the building will the ball land?

3 answers

the free fall equation is
... h = -4.9 t^2 + 50

set h = 0 and solve for the flight time

multiply the flight time by 20 m/s to find the impact spot
I got an answer of 63.8m is it correct
to three figures ... 63.9

do you use significant figure rules?