Recently a video was posted by science fiction writer Rikao Yanagida which, using a scene from the much-loved Studio Ghibli movie, Kiki’s Delivery Service, attempted to gauge the upper-body tensile strength of the titular character.

The scene used for Yanagida’s analysis came from the climax in which Kiki catches Tombo mid-fall after slipping off a rope attached to a blimp. According to Yanagida’s calculations, to be able to make such a one-handed catch while clinging to the broom, Kiki would have to withstand a force of 44 tons!

That’s a seriously impressive feat of strength. But before we go patting Kiki on the back, let’s go over Mr. Yanagida’s work.

In the video, Yanagida says that Tombo falls for three seconds in Earth’s gravity which would work out to a distance of 44 metres.

We can also confirm the fall was three seconds by this fan made video (3:07 to 3:10).

Yanagida also judges that the fall comes to a stop 50cm after the catch. This is a bit of a misstep as Kiki never comes to a complete stop. However, she does slow down considerably which makes the difference negligible.

According to Yanagida it would require 88 times Tombo’s weight to stop him falling in 50cm.

He then estimates Tombo’s mass to be 50kg, which seems a little high but within reason, and calculates his force to be 44 tons.

So it would seem that Yanagida had some trouble with units when he said 44 tons or 44,000kg. In fact, the force would be 43,000 Newtons which would equate to about 4.4 tons or 4,400kg in terms of mass. Nevertheless, that’s still an impressive amount of weight to haul, equal to about a full-grown male African elephant.

However, there is a more fatal flaw to Yanagida’s calculations. This is all under the assumption that Kiki isn’t moving when she makes the catch, but if we review the video, she’s also traveling downward at a speed faster than Tombo.

If Kiki weren’t moving and hanging on the broom then the force would be applied to her as demonstrated in this highly complex RocketNews24 computer simulation.

However, Kiki is also a body in motion and most of the stopping force would be applied to whatever the heck kind of magic is keeping the broom up, rather than her.

It’s as if I were going to catch a skydiver. If I was standing on a building with my arms stretched out the diver would tear them off. But if I was also sky diving I could easily catch them. Also, if I were to deploy my parachute it would still take some force to hold the other person, but not nearly as much as the first case.

All that being said, Kiki would still need to be in considerably good shape to be able to catch and hold onto a boy, who likely weighs more than her, with only one arm. We should also give Rikao Yanagida credit for sparking some interest in good old fashioned physics.

I now submit this study for peer review by other internet physicist wannabes like myself.

Source: Kotaku via Hachima Kiko (Japanese)
Kiki Video: YouTube – Sarah J
Video: NicoNico Video