A stone is dropped from the roof of a building; 1.50 s after that, a second stone is thrown straight down with an initial speed of 24.0 m/s , and the two stones land at the same time. How long did it take the first stone to reach the ground? V=Vo+aT I plugged 1.5 s for time, 9.8 m/s^2 for acceleration, Vo=0 initial speed. Got 14.7 m/s for velocity and plugged it back in the equation for velocity to find the time for the drop. I got 4.9 sec.