An 81 km/h Catch!? The Physics of Love Behind Kiki’s One-Armed Grab (Kiki’s Delivery Service)
I am Ken Kuwako, your Science Trainer. To me, every day is an experiment.
Do you remember the climactic scene in the movie Kiki’s Delivery Service that had everyone holding their breath? It is that heart-pounding moment when Tombo falls headfirst from a runaway airship, and Kiki, riding her broom, catches him in mid-air just in the nick of time. While most people were cheering her on, my science-loving brain couldn’t help but worry about something else entirely: “Wait… is Kiki’s arm going to get ripped off!?”
Behind that emotional rescue lies some truly terrifying physics. Catching a human being falling at over 80 km/h with a single arm requires a level of power that is hard to imagine. This time, I sat down with a stopwatch, counted the animation frames, and used the laws of Momentum and Impulse to run a realistic simulation of that rescue. Does the power of love actually defy the laws of physics? Let’s dive into the shocking results! 
The fateful moment Kiki catches Tombo! If we zoom in…
Calculating Tombo’s Falling Speed Down to the Second!
First, let’s figure out how fast Tombo was actually falling. Watching the movie, about 3.5 seconds pass from the moment Tombo lets go of the rope until he is caught. However, we have to account for cinematic flair. You know those shots where the camera zooms in on the shocked faces of the crowd in slow motion? 
If we subtract that dramatic padding (about 1.20 seconds), we can estimate the actual physical fall time was roughly 2.30 seconds. Using the formula for velocity v = gt, where gravity g = 9.8 m/s², we get:
Converting this to hourly speed, it’s about 81 km/h! That is roughly the speed of a professional baseball pitcher’s breaking ball. Tombo was essentially a human projectile slamming into Kiki’s arm.
The Impact on Kiki’s Arm was 3,900 Newtons!?
Now for the real physics: Momentum and Impulse. Kiki caught Tombo as he lunged at 81 km/h and brought his velocity to zero (a dead stop) almost instantly. Measuring the time from the catch to the stop, it took only 0.33 seconds! Assuming Tombo weighs 50 kg, let’s calculate the average force exerted on her arm.
Calculating the Change in Momentum Since Change in Momentum = Mass × Change in Velocity:
Solving for Force (Using the Impulse Formula)
But wait, there’s more. Even after stopping him, she has to support Tombo’s weight against gravity. Gravity W = 50 × 9.8 = 490 N. Adding it all up, Kiki’s arm was hit with a force of approximately 3,905 N at the moment of the catch. To put that in perspective, that is roughly 398 kg! In an instant, the weight of about eight Tombos was suddenly hanging from Kiki’s single arm.
For a normal human, this would result in a dislocated shoulder or severe muscle failure. A witch’s physical durability is truly something to behold!
Actually, the “Other Hand” Holding the Brush is Even More Incredible
What’s even more surprising is Kiki’s other hand. While she supports Tombo with one arm, she is gripping the deck brush with the other to maintain lift.
The hand gripping that brush has to handle Kiki’s own weight plus the massive reaction force from supporting Tombo. Continuing to fly while enduring that desperate load… that isn’t just muscle. It’s a “will to save him” (magic) so strong that it expanded the very limits of physics. The reason that scene moves us so deeply might be because Kiki is overcoming an impossible physical trial through sheer love and grit.
Physics Reveals the True “Scale” of a Story
When you use a stopwatch and equations on famous anime scenes, the superhuman nature and the weight of the characters’ resolve become so much more real. There are countless seeds of science scattered throughout entertainment. If you look at the world through the lens of “What if this were real?”, your favorite movies become even more fascinating.
Kiki’s Delivery Service was recently broadcast on TV, and I’m sure many of you tuned in. I love Ghibli films myself and have visited the Ghibli Museum in Mitaka several times. Among them, Kiki’s Delivery Service is a wonderful piece that teaches you different things depending on what stage of life you’re in when you watch it.
As for me, I found myself calculating the magnitude of the force acting on Kiki’s arm during that final rescue scene.
While I was doing chores and watching the re-run, looking at the town and the rooftops reminded me of the streets of Visby on Gotland Island, Sweden. I visited there once. This town was one of the inspirations for the setting of the movie. Here is a photo I took:
It’s a small town surrounded by walls with a history of trade and war. I took this from a hill next to a church. The beauty of the town and the elegance of the arch structures are striking. Walking through it really feels like you’ve wandered into the world of Kiki’s Delivery Service.
There was even an exhibit showing the strength of arch structures. I’ve summarized that here if you’d like to take a look:
Gotland Island is a bit out of the way to get to, but if you’re a Ghibli fan, it’s absolutely worth the trip. Definitely consider it for your future travel plans!
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