The building is approximately 57.1 meters tall.
The height of the building can be determined using the equations of motion for free-falling objects. When an object is dropped from a certain height, its position can be described by the equation h= 1/2gt^2, where h is the height, g is the acceleration due to gravity (approximately 9.8 m/s²), and t is the time of fall.
Given that the rock hits the ground 3.5 seconds later, substituting t=3.5 seconds into the equation gives h= 1/2×9.8×(3.5)^2. Solving this expression yields a building height of approximately 57.1 meters. Therefore, the building is approximately 57.1 meters tall based on the time it takes for the rock to fall and hit the ground.