it didn’t fall like a rock, the north tower was hit first and stood for over an hour and a half because the plane hit higher up, the south tower despite being hit second collapsed first, because the plane hit about 20 floors lower and that building still stood for 56 minutes until the tipping point was reached sooner than the North tower because of the greater load on the structure.
• 8:46 am – Mohammed Atta and the other hijackers aboard American Airlines Flight 11 crash the plane into floors 93-99 of the North Tower of the World Trade Center, killing everyone on board and hundreds inside the building.
• 9:03 am – Hijackers crash United Airlines Flight 175 into floors 75-85 of the WTC’s South Tower, killing everyone on board and hundreds inside the building
• 9:59 am – The South Tower of the World Trade Center collapses.
• 10:28 am – The World Trade Center’s North Tower collapses, 102 minutes after being struck by Flight 11.
Now watch the north tower collapse it takes almost 30 seconds from the 32 sec. mark in the video to after 1 minute
https://www.youtube.com/watch?v=3gAnDDukdj4
now based on science and physics gravity accelerates an object at 32 feet per second per second or 9.8 meters per second per second. The WTC was about 1300 feet tall, a rock would free fall that distance in about 9 seconds, less time than the building took to collapse, actually if you look closely you can see that the building debris that falls away from the building falls away faster than the central ‘core’ of the building which is slowed slightly by the progressive failure of each floor as the cascading failure occurs.
You can count the fall time from beginning to end from the public video. It is the time calculated to take a rock dropped from that height to reach the ground.