ELi5: How come ants can survive almost any fall but humans can’t?

437 views

I know it has to do something with mass, but i’m clueless.

In: 0

13 Answers

Anonymous 0 Comments

As things fall the air pushes against them; slowing them.

Terminal velocity is the equilibrium of gravity and air pushing on you in opposite directions. At a certain speed you will stop accelerating because the air is slowing you down at the same rate that gravity is speeding you up. That’s called **terminal velocity**

Terminal velocity is different for every object, and it mostly depends on

-mass (weight)

-surface area (how much surface there is for the air to push back on)

The ratio of these is essentially what decides your terminal velocity. Humans have a large mass:surface area ratio compared to ants, so gravity will accelerate a human in a free fall to a speed far greater than an ant. Ants have a low mass: surface area ratio so they will fall at speeds far lower than humans

Anonymous 0 Comments

Terminal Velocity.

Basically there is a point when falling where you no longer pick up speed. Due to a bunch of math reasons ants hit this almost immediately upon falling. The impact does basically no damage to them. so, it doesn’t matter If you drop them an inch or off a skyscraper they still fall at the same rate and speed and thus the impact is the same.

humans for instance take longer to hit terminal velocity and impacts are fatal long before we hit it.

Anonymous 0 Comments

Reason 1: square cube law on impacts: All the weigh of the ant tries to splat the ant at impact. But the weight is very small.

If you take an ant and scale it up to be 10 times bigger, then the volume of the ant will be 10*10*10 times bigger. The weight will be 1000 times bigger. Now the scaled up ant has to take 1000 times more impact force. And this force will be spreaded on a surface that is only 10*10 bigger. So, the pressure in the impact is already 10 times more (force per square inch). There’s 10 more lenght of legs to absorb the hit, but that’s not gonna make a difference to the impact on the foot. That’s why a fall on your foot will let you uninjured in the head but the hit to the foot will break the foot or ankle or knee.

You can scale it up more and more and you see how big the difference becomes. A 100 times bigger ant has 100 times more pressure per square inch. The chances of damage go up, at that pressure the tissues will be squeezed (what happens when you take a hit and your skin becomes blue, that’s dead tissue). There’s 100 times more leg lenght to absorb the hit, but again it won’t work to save the first part that hit the ground.

Reason 2: Square cube law also affects terminal velocity.

Ant: 1 weight 1 surface to make air drag.

Ant 10 times big: 1000 weight, only 100 surface that makes drag.

Ant 100 times bigger: 1million weight, only 10k surface to make drag.

The bigger the object the more it wins versus air resistance. This gives higher and higher free fall speeds.

Conclusion: So an ant will fall slower and with less mass than a human. This give a lot less impact forces.

Of course this is all dumbed down trying to reduce the variables.

If you don’t believe me have a look to a scooter hitting a scooter at 10kmh (paint damage) and a ship hitting a ship at 10kmh (both sink). A ship hitting a ship will make a different type of crash. Cause the mass involved grow cubic while the area that takes the hit grows squared. And again the extra lenght to absorb the impact does not apply to the first contact point. It may save the parts further back, but this is possible if the first parts to hit don’t collapse.