This video showing how it is possible to pour water upside down has gone viral, but how is it possible for the water to move in that way?
Take a glass of water, and turn it over. What you have not done, right? Because you know that you are going to throw the water on the ground and cause a mess, because you know that gravity is something that exists and that it will always exist in our lives.
But what if you could beat gravity? It’s not as spicy as it sounds, we do it daily taking advantage of all kinds of forces that keep objects off the ground without the need for magic spells.
Demonstrating what can be done on a fighter
That is the case of the video that we have below, in which we see the occupant of a fighter demonstrate what can be done with a simple glass of water and some maa:
As you can see, when the fighter performs the 360 rotation, it is perfectly possible to pour a glass of water from a bottle; in fact, if we look at what happens in the background, we would think that the fighter is not moving. Even it is perfectly possible to drink water upside down, although in that case our sphage is largely to blame.
The control that the person has is partly to blame for it seems so simple (when in fact it is not easy to withstand those G forces and act as if nothing), but the reason why the water does not follow the path of gravity and crashes with the roof of the fighter is another: centrifugal force.
Centrifugal force appears when you make a circular movement, like the one that the fighter does, and pushes all the objects that are on the platform that moves; Although the centrifugal force tends to move objects away from the axis of rotation (that is why the centrifugal force is said to be outward), in this case other variables such as gravity must also be taken into account.
How is it possible to pour water upside down
The result, putting all these force vectors together, is that water tends to go towards the center of the axis of rotation; It’s easy to confuse this with centripetal force, and I actually thought about it myself when I first saw the video. From childhood we were taught that the centripetal force is the one that goes inward, and therefore the one that attracts objects to the axis of rotation.
However, there is a great detail that we cannot ignore: the centripetal force is always an external force, which acts on the object directly, does not occur naturally when movement occurs as the centrifugal force.
For example, a hammer throwing athlete spins for speed; at that moment, the weight undergoes a centrifugal force that pushes it to escape, but at the same time it undergoes a centripetal force through the rope that joins it to the athlete’s hands. It is the athlete himself who effects that force, and therefore It is not characteristic of rotational movement.
All this is to say that, although the video shows that the water is moving towards the theoretical axis of the rotational movement of the fighter, this movement is not caused by the centripetal force, but by the centrifugal force. Although of course, if you ask a physicist it may say that in reality the centrifugal force does not exist either because the objects always want to go in a straight line, and at that moment your brain does caput.