How is it that bugs take no fall damage?
In: Physics
I’ve heard that cats are the same (not willing to test), their fur slows them down enough to prevent fall damage.
Late to this party but here is a video by Kurzgesagt explaining this very thing perfectly!
Bugs are Small so no fall fast. No fall fast means doesn’t splat hard. Bugs don’t splat hard.
Additionally, beetles have a protective shell encasing their squishy bits. Because they’re so small, they need armour to protect themselves from damage that would otherwise kill them. Humans are complex enough that we can heal bruises instead of dying from them, so we don’t need armoured skin.
To break anything you need to spend a certain amount of energy, depending on the material it is made. It’s easier to break the shell of chocolate egg by hitting it , than it is to break a baguette, than it is to break a cube of steel.
Every material needs a certain amount of energy to break its structure.
Energy is greater when the speed of the moving object is greater and when the weight of the moving object is greater.
A bug is very light. Its weight is very small. Thus when falling from a table, the energy it gets from the speed is smaller than for example an egg gets.
Also, a bug’s shell is made by cythin which is extremely durable. You know that when you try to squash a bug, you need to make some effort. That energy you spend to squash a bug is higher than the energy the bug has during the fall.
So you get a creature that is small, light, which is also extremely well armored. The fall energy it gets is not enough to break its shell. It’s smaller than what your finger can produce to squash it.
Basically same way we don’t damage using parachutes. Some bugs have simply air friction and weight ratio that it’s like having a natural parachute at all times.
To a such bug, air is more like a liquid, so it falls through it like you would sink into a deep lake. Even if lake is super deep – like 15 stories deep, you still won’t crash the bottom of the lake in the end, water slows you down so much all the way.
Even though acceleration by gravity is same, water limits the speed you end up with (called terminal velocity) much more than air would. But if gravity was – 10 times stronger – say – on different a planet or whatever, you could totally splat to the bottom of such lake and water friction couldn’t overcome it enough to save you.
Fall damage is the body being unable to keep up with the massive forces required to bring an object to a stop in a short period of time. For a human, trying to stop 100lbs within 5 feet (a **20:1** ratio for my example human) gets tough pretty quickly depending on how fast they are going. According to a brief google search, the average house fly weighs something like .00001lbs and is .023ft tall (a **1:2300** ratio). So the ratio is like 23,000 times better for them to start with. IE: bugs have less weight to decelerate in a relatively longer period of time (if we assume the two creatures are falling at the same speed)
However, another result of this smaller weight, is that air resistance becomes a much bigger factor when falling. A tiny little updraft can make the insect lose almost all of its downward momentum, and their terminal velocity is much slower as a result. So even though my previous paragraph assumed that the human and bug were falling at the same speed, that’s almost impossible. A bug will fall WAY slower.
Not only that, but there’s something called the Squared-Cubed law which says things like “if something doubles in height, it usually multiplies its weight by around 8” and that has further implications for our comparison. One effect of this is that while large creatures may have stronger bones compared to small ones (you don’t see us getting flattened by a fly swatter, for example), but a lot of that strength is spent simply keeping us upright in the first place to counteract the massive increase of weight our size comes with (see that ratio I posted earlier), so when something like a human is met with an impact, that force is being added on top of the strain our bodies are already under as we maintain our own shape. A bug barely has to spend any energy maintaining its own structure, so nearly all of its strength can be devoted to absorbing the impact properly.
So yeah, with all of that combined, comparing the amount of damage a human takes from a fall vs an insect, any damage the bug takes would be basically nonexistant compared to what us humans are used to.
The terminal velocity of an object, aka the fastest a thing can fall before air resistance stops it from speeding up any more, gets bigger with weight, and smaller with cross-sectional area (you can think of cross-sectional area as just, how much of the object you can see from one direction).
This means heavy things fall faster, and wide things (like paper when its wide side is facing down, or a frisbee) fall slower.
Now, weight increases according to how big a thing is, and so does area **but** they increase a different speeds.
Imagine you have a single cube. Now imagine growing that cube so each edge is twice as long as the original.
To fill this new, bigger cube, it takes *8 of the original cube* (2 cubes along each edge). This makes the cube *8 times as heavy*.
On the other hand, each side of the cube only takes 4 of the original cube’s sides to make. This means the cube’s *cross-sectional area 4 times as big* as the original.
From those examples, you see that increasing something’s size increases its weight faster than its cross-sectional area.
This holds in reverse too. Shrinking something shrinks its weight faster than its area.
Now, remember that bigger area means slower fall, and bigger weight means faster fall.
If you take a human, who falls fast enough to hurt a lot, and shrink them down to the size of a bug, their weight will shrink a lot more than their area, so in turn, they’re going to fall a lot slower than a normal human.
This is most of the reason that bugs “don’t take fall damage”, as you said.
When you fall you push air around you. Feel it with your hand. The air is also pushing on you. When a bug falls, the air pushes against it too hard for it to go fast because it it so small and light. Drop a leaf and a rock, observe.
Edit: Gravity pulls on the leaf and rock equally.
Speed required to damage them is greater than maximum falling speed possible due to air friction
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