It depends on the height of the building and also on the direction the object is thrown in (up, down etc.).
We have no idea how big the rock is, and no way to figure it out. But we can calculate that it reaches 11.48 meters above the ground before it starts falling.
time is 1.5 second
They should reach the ground together, since their initial vertical speed is the same, namely zero.
An object thrown vertically up wards from the ground returned back to the ground in 6s after it was thown up if it reached a height of 12m calculate?
The height, in feet, above the ground at time t, H(t) = 40 + 32*t - 16*t2
The answer depends on whether the ball is thrown vertically upwards or downwards. That critical piece of information is not provided!