Answer:
Explanation:
If we make a rather silly assumption that the runner does not leap upward somewhat as he leaves the edge of the first building, his initial vertical velocity is zero.
The time needed to drop 5 meters from vertical rest is
t = √(2s/g) = √(2(5)/9.8) = 1.01 s
so he needs a horizontal speed of at least
v = d/t = 8 / 1.01 = 7.91959...
v = 7.9 m/s. Better make it 8 m/s to be sure he clears the edge and lands on the roof.