I'm sure you ask yourself almost every day How much does a truck weigh with birds flying inside?. In fact... Would the Earth weigh the same if all the birds took flight at the same time? We can ask ourselves the same questions with that truck. Or even if you want to take your Andean condor to the vet but it weighs too much to be able to transport the cage easily, you can think that perhaps if you transport it while it is flying inside the cage you will save those 15kg that your exotic pet weighs and illegal.
Is that true? Does a truck loaded with birds weigh less when all the birds are flying inside?
The answer is simple: No. It weighs the same as when all the birds are resting on the ground.
The explanation is not that much, but I think it is not too complex to follow the thread of it either.
Explanation: Does a truck loaded with birds flying inside weigh less?
This very counter-intuitive idea about the weight of a container with birds flying inside was put to the test by The MythBusters on their American television show, and they found the incredible answer that the truck always weighed the same. whether the birds were flying or not.
A later and much more precise study was carried out and published in the journal of the Royal Society by David Lentink, Andreas F. Haselsteiner and Rivers Ingersoll. In this article These engineers from Stanford University use a drone to demonstrate with scientific rigor that the forces that birds (or any body that rises in the air) generate to stay in the air end up replacing the weight previously exerted by their own bodies, since that weight is another force, and requires a force in a negative direction (towards the ground) to create a (positive) impulse that raises the birds' body.
Although it may not seem like it, air is a fluid, and with the same physical formulas that could have measured the pressure exerted on water when swimming, they calculated the air currents and pressure that birds create during their flight. In this way they reached a similar conclusion, but not exactly the same one that the Mythbusters reached: The weight of the truck remains stable on average, but in a constant and imperceptible swing in which it alternates between weighing less than it should, and weigh more.
In the following graph you can see the different measurements and results obtained, in which a weight imbalance is clearly seen throughout the entire experiment. During some moments the weight of the truck is slightly above what was expected, and symmetrically, during the rest of the moments the weight of the truck is below what it should be.
The weight of a truck with birds – Conclusion
This very anti-intuitive idea for the human brain turns out to be a very interesting experiment on the physics of fluids, where it is possible to answer the question initially posed: Does a truck transporting birds weigh the same when they fly inside the vehicle?
If you want, you can leave a comment to add or refute any information that you think is incorrect or can be improved., and access more curiosities on the blog.
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