I was on YouTube and went down the YouTube rabbit hole. Ended up watching a [compilation](https://youtu.be/WDY7uD4E8p4) of water towers collapsing. That’s what sparked this question. It’s portrayed well in movies when a giant monster is destroying a city. It seems as if Godzilla is moving in slow motion. Anyone know why this phenomenon occurs?
In: Physics
Also, large objects that are falling are probably further away so they appear to be moving more slowly.
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Your eyes and brain are sort of stupid. One way we tend to gauge speed is by how quickly an object moves across our visual field, which is to say the angle it covers from our point of view.
The problem is that the distance an arc sweeps out depends on how far away on the line you consider the arc to be. A very distant point means a much greater distance the arc covers; this means distant objects will cover a lesser apparent arc than a closer object moving at the same speed.
Very big objects viewed from a great distance away might be moving quite quickly, yet still only cover a small angle of our vision. Our dumb visual processing doesn’t know how to accurately gauge long distances, or do the geometry to figure out the real speed of such distant objects like we can usually manage in closer interactions.
Two things. Inertia and perspective.
Inertia. If an object have more mass, it have more inertia. Meaning that it will resist movement more. This is why it’s harder to get something to start moving when its bigger. This is why those tower move really slowly at the beginning and then start to fall faster.
Perspective. What you are looking is high, so you need to be further aways to see it completely. The speed at which the tower fall is as quick as anything else (once it get starting), but you see it from further aways so the distance see smaller to you. It’s the same reason why when you look outside your car’s window you can see the building next to the road go past you really fast, but the mountain far aways move slowly.
Gravity acts with equal force on all objects. Yes, those objects with more mass have more to be pulled but they also pull back with greater power. So in short, all objects have constant acceleration. There are some ways in which objects can fall slower if their shape means they have maximised air resistance compared to their weight (think a piece of paper or a feather) but in practice most items will fall at approximately the same speed because of this.
The difference comes when you consider the scale of items. You might think that an item which is one meter tall should collapse in the same time that something 100 metres tall collapses, but this would be to forget that both items fall at the same speed *but one has much further to go* – one hundred times further, no less. It won’t take 100 times longer because it will accelerate and accelerate in a way that the 1m object didn’t have time for, but it still has to take a long time to cover that distance. The thing is, you end up standing a long way away from the object so you can watch it fall safely, and that means that you forget just how far it has to travel, making it seem very slow. It’s just a case of perspective and scale, though.
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