A collision at a speed of 120 km/h, does that correspond to a fall from the 3rd floor of an apartment, the 8th or the 19th?

Answer

That of course depends on how many meters a floor is in vertical direction. But the speed of a falling object, in the absence of air resistance, is very simple

v = gt

and the distance traveled is x = 0.5 gt²

If you combine the two by eliminating time you get:

v = square root ( 2 gx )

Now suppose that one floor is 3 meters, and you fall from the 8th floor, then you fall over a distance x = 24 m. With the above formula, and g = 9.81 m/s2, your speed below is therefore equal to 21.7 m/s and that is 78 km/h

From the 19th floor that becomes 33.4 m/s and that is 120.4 km/h