Answer & Explanation
We can find the speed corresponding to the apparent frequency and then use that to find the height of the building.
120 = 100(330)/(330-v) v = 330 – 3300/12 = 55m/s.
Using, v² = 2gh, we can find the height covered by the man. The double of this value will be the height of the building as he is mid-way.
55² = 2*9.81*h h = 154m Height of building = 2h = 308m.