Like if I knock over a toy car, it seems to happen quickly, but a large building collapsing seems to happen “slower”?
In: Physics
When you knock over a toy building it only has to fall a couple of feet. When you knock over a real building it has to fall hundreds of feet. Suffice to say that it takes longer for the building to fall those hundreds of feet, so if you compare it to the smaller version then I suppose you could compare it to slow motion, but it’s simply that the scales are larger and so things take longer to complete that distance.
It’s the same reason that big things like trucks or airplanes look like they’re going much slower than a car even if they’re actually going faster…we estimate speed by comparing how things are moving against their background and we’re wired up to accurately track speed on human-sized objects so our sense of speed scales with the object size.
Things that are really big or small screw with our sense of scale…rather than realize that the object is really big and just moving really fast, our brain assumes it’s “normal sized” and moving slower. Really small objects go the other way…they look like they’re going faster than they really are.
It takes 1 second for the top of a 32 foot building to hit the ground under gravity, 3.16 seconds for a 320 foot high tower. Assume that you are standing 10 times further away so the perspective makes them both appear at the same vertical angle of view to you, then as they collapse that angle changes more slowly for the taller, more distant building.
Something to add is a clarification on building collapses, particularly other than the knock-over type, but those as well. While a small toy or what have you can just be knocked over in one go, buildings rarely, if ever collapse by failing everywhere within their structure all at once. Generally, you’ll have a small (large if you’re near it, I suppose!) failure and then another and another.
Sometimes it is the added stress (that which was borne by the now broken members) which must be borne by the remaining members which causes subsequent breaks. Other times, all the members were going to break, but they are simply offset in time because…what are the chances they wouldn’t be? All kinds of things from extreme stretching (deformations) to fracture mechanics (how things snap) have to take place everywhere anything will break. This all takes various amounts of time and places “drag” on the “speed” of the collapse as things “hang on” momentarily.
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