Object is dropped from the top of a building that is 1125 m tall at the point when it’s speed is 30 m/s how far has it fallen

-- Gravity makes a falling object fall 9.8 m/s faster every second.

-- So, it reaches the speed of 30 m/s in (30/9.8) = 3.06 seconds after it's dropped.

-- The distance an object falls from rest is D = 1/2 (acceleration) (time)²

D = 1/2 (9.8 m/s²) (3.06 sec)²

D = (4.9 m/s²) (9.37 sec²)

D = 45.8 meters

Notice that we don't care how high the building is.  The problem works just as long as the object can reach 30 m/s before it hits the ground.  That  turns out to be anything higher than 45.8 meters for the drop . . . maybe something like 13 floors or more.

Now I'll go a little farther for you !  Writing the last paragraph made me a little curious and uncomfortable.  So I went and looked up the world's tallest buildings . . . and I found out that this problem could never happen !

The tallest building in the world now is the Burj Khalifa, in  Dubai.  It has 163 floors, and it's 828 meters high !  That's 2,717 feet.  It's gonna be a long time before there's a building that's 1125 meters tall, like this problem says.  That's close to 3700 feet . . . I've had flying lessons where I wasn't that far off the ground !