On May 26th, 2018, it was reported in the French news that a four-year-old child fell from the 5th floor’s balcony of a building in Paris (France), and was able to catch the railing of the 4th floor’s balcony.
I wrote a preprint (https://arxiv.org/pdf/1807.05502) in which I make a calculation that shows that such an exploit is impossible. Of course, in order to make this calculation I need to idealize the situation. The result is that the scenario is VERY FAR from being possible, as the 4-year-old child would need to apply an average force of 1176 N to stop his fall. Moreover, the instantaneous force could easily reach a value that is an order of magnitude greater. It is hard to believe that small corrections to this ideal situation could make it possible. In addition, based on the declarations of the concierge of the building and the child's father, the child would actually have fallen from two stories instead of just one, which makes the scenario even worse.
As opposed to many remarks that I received, I didn't forget about frictions forces and air resistance, I simply showed that these forces are negligible compared to the gravitational force.
Now, do you really believe in the scenario reported in worldwide news?
Better to ask the person who was able to catch it. Generally it is impossible.
So, the scenario is hard to believe. Especially when the concierge of the building declared later that the 5th floor is uninhabited and that the child leaves on the 6th floor. So he would have fallen from two stories.
Better if you had a photo of the railings. Perhaps the railing is wide and caught the child. Perhaps there was some netting or the child was dangling from a rope it was playing with. The news has to make normal things glamorous by leaving out details.
There is a video of the railings with the child and Mamoudou Gassama climbing in the first reference in my preprint. I know that people like to stick to the idea that "friction with the net on the railing" helped slowing down the fall. But we have to be reasonable. As physicists, we all know that as soon as the child starts to slide down, there is indeed some kinetic friction proportional to the normal force of the surface of friction. However this normal force is basically zero, since there is no force that pushes the child against the railing. As soon as he slides down, if there is any friction, the child will pushed away from the railing, instantly canceling any further friction with it.
Another common argument is that the child's legs could have touched the railing first. Again, such a scenario is crazy:
- The railing of the lower balcony has the same (x,y) coordinates as the one from which the child fell. The center of gravity of the child clearly cannot have the same (x,y) coordinates. Thus if his legs touched the lower railing, then his upper body would be even further from the railing, so he would fall backward, without any possibility of catching the railing with his hands.
- Even if we involve a magic force that prevents him from falling backward, can you just imagine the pain of falling from a height of 2.5 m onto a railing? That contradicts with the fact that they stated that the child only had a torn toe nail.
- In addition, do you really believe that the force involved in tearing a nail could compete with the gravitational force?
I personally dont believe a child fell just because a newspaper claims it is so....
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