Science Fact, or Cinematic Fiction? Horton Hears a Kung Fu Robot!

Horton Hears a Kung Fu Robot


When the only force acting on an object is gravity, it will follow a parabolic arc when it falls. The animated films Robots, Kung Fu Panda, and Horton Hears a Who, all depict at least one scene where a jump or fall is animated incorrectly according to the laws of physics. These errors can be found in one scene from each movie. The most commonly found errors in these three scenes related to the path of action, angle trajectory, spacing, and speed changes.
In the 2005 animated film feature, Robots, the main character, Rodney, takes a unique form of public transportation called the “cross-town express.” In the Robots universe, characters board the cross-town express by climbing into round metal chambers. These chambers are then catapulted to various destinations in the city. Through careful observation of this scene, it is clear that the path of action, trajectory, spacing, and speed of the catapulted chamber are incorrect according to the laws of physics. First of all, the chamber does not follow a parabolic arc. Instead, it looks as if it is catapulted at a 45° angle, then jumps vertically on its path of action. It then continues moving in a slightly angled straight line. The path of action for this fall seems to be more of a shallow wave ending with a straight line of action, when in reality it should be a long, shallow parabolic arc. The speed of the metal chamber is also incorrect.
Tangential speed is also related to the distance the chamber travels. However, the tangential speed of the throwing arm on the catapult is incorrect. If the chamber moves fast on the catapult, it is more likely to move faster in the air when it is released. The catapult’s arm would have to be longer for the cross-town express to fly as far and fast as it does in the sequence. Observing just the animation, it is clear that the speed changes are due to the spacing of key frames and in-betweens.
Whenever the chamber is moving slower, there are more frames and they are closer together. This differs from when the ball looks as if it is moving fast, which occurs when there are fewer frames and they are spread farther apart. However disloyal this sequence is to the laws of physics, this exaggeration of spacing and timing makes the animation entertaining. Such is also the case in a scene from Kung Fu Panda.
The final fight scene in DreamWorks’s 2008 animated film, Kung Fu Panda, also demonstrates an incorrect use of parabolic arcs. Such errors include an incorrect path of action, mid air suspension, and the unrealistic speeding up and slowing down of falling characters. In this scene, both Po and Tai Lung leap off a building, and struggle to catch a golden “sacred” scroll. First of all, Tai Lung and Po do not follow parabolic arcs. After Po leaps off a couple airborne roof tiles, his path of action travelling towards the apex is almost a completely straight line with a small angle. Po stays suspended mid air while Tai Lung leaps straight up. After Tai Lung reaches his apex, he hooks around (still suspended mid-air) to drop kick Po. In reality, Tai Lung would have fallen far behind Po. Additionally, Po would have fallen to the ground at least three seconds before Tai Lung even leapt into the air. Furthermore, both fall straight down after they reach the peak of their jumps. In nature, they would complete a parabolic arc, and travel much farther horizontally than where they landed in the scene.
The timing of the fall is also flawed according to the laws of physics. Both characters appear to pause mid air, then dive straight down rapidly. In reality, they would complete their parabolic arcs, slowing in and out at the apex, and then accelerating to the end of their fall. Moreover, the speed of both characters increases abruptly when they start falling to the ground. After Po is drop kicked, he speeds to the ground by the force of Lung’s attack. After that, Lung dives after him mid as if he is diving into a pool. Even though this is not physically possible, the animation was designed to exaggerate the falls and jumps for dramatic effect, so lots of anticipation was used. The anticipation shown in the sequence is incorrect according to the laws of physics, but it makes for strong storytelling. Such is also the case in a scene from Horton Hears a Who.
The animation in Horton Hears a Who was pushed to intelligent and entertaining extremes. However, the exaggerations do not adhere to the laws of physics. The most noticeable physics error can be found in the scene where Horton runs through the jungle to catch a speck. While Horton is stampeding, a monkey tribe catapults a banana boulder at him, which falls incorrectly according to the laws of physics. First of all, the boulder does not fly in a parabolic arc. Instead, it’s launched at what looks like a 60° angle, which would take the boulder half as far as it travelled in the film. Conversely, the banana boulder flies in a straight line for almost two seconds, and subtly hooks to the left of Horton before it impacts the ground. Surprisingly, the hooking is not the only strange movement incorporated in the banana boulder’s path of action. In addition to hooking, the boulder appears to move in three long vertical waves. This is only obvious because of the manipulated timing of the boulder’s fall.
The tangential speed of the catapulted banana boulder is incorrect. For it to move that fast, the catapult would have to be longer. However, if the catapult were longer, the boulder would achieve more height in the air, causing it to land even earlier than it does in the scene. Moreover, the speed of the banana boulder changes mid air four times. In the sequence, the boulder catapults into the air at a high speed, slows down twice-mid air (progressively getting slower), and speeds up before it impacts the ground. This would not occur if the boulder were falling in reality. In nature, the banana boulder would speed up as it is catapulted, slow a little at the apex, and then speed up again it approaches impact. However incorrect this sequence might be, it is highly comedic, and any flaws in the physics of the sequence only enhance the entertainment value. This is the case with all three films.
Most physics errors are well disguised in Robots, Kung Fu Panda, and Horton Hears a Who. Interestingly, the same errors were present in all three movies. In defense of the films, these physics errors could have been intentional. The dramatic pauses, changes in time, and height give the scenes anticipation, one of the most important principles of animation.