#5. Watermelon Exploded By Rubber Bands
The watermelon’s outer wall is usually pretty rigid and durable. Slowly wrapping rubber bands around it gently increases external pressure, which is squeezing the interior of the watermelon onto either side of the rubber band, increasing the pressure on those other areas. Notice also how they go along the short side, which is weaker than the longer one. At around 500 rubber bands, the external pressure eventually forces the watermelon to distribute so much internal pressure to the upper and lower shells that it cracks the outer wall (notice how the first crack appears at the very top, and that’s quickly followed by a crack a couple inches above the rubber bands. Those were weak points). And without watermelon inside, the wall is much easier for the rubber bands to break. After they’ve gone through the wall, the flesh of the fruit provides little resistance, so they snap and transfer all the force to the melon from the inside, which makes it explode outwards. Here is the original video from the Slow Mo Guys.
#4. Lunar Phases Assembled
One full revolution of the Moon around the Earth takes about 29.53 days. In this time it goes through several phases, all of which are characterized by the portion of the Moon that’s visible to the Earth. In the new moon phase, the Moon stands between our planet and the Sun. Since the Sun is the only major source of light in the Solar System, the moon is in shadow. (That faint brightness on the moon around this time is because of earthshine—sunlight reflecting off the Earth onto the moon.) At the opposite end of this cycle, the “Full Moon” phase, the Moon is on the opposite side of the Earth, illuminated by the Sun, and thus we see the entire side of the Moon that always faces us (thanks to tidal locking). Here’s some good reading material on lunar phases.
#3. Glass Fracturing At 10 Million FPS
Glass is a peculiar material. It’s incredibly durable to compression, to the point where to shatter a cube of one cubic centimeter, you’d require a load of 10 tons. Regardless, the average tensile strength of glass is very low, making it amazingly weak against fast and focused blows. Scientists have yet to discover exactly how glass shatters on an atomic level, but at least we can enjoy these beautiful fractals while we’re waiting for them to figure it out. Here are some theories about how glass breaks.
#2. Non-Newtonian Fluids
Unlike regular fluids, non-Newtonian fluids change their behavior based on your interaction with them. For example, when one type of non-Newtonian fluid is introduced to high stress, like a fast hit, its viscosity increases, and it thickens up to act like a solid. This is because the particles inside a non-Newtonian fluid are many times larger than in a regular fluid. When exposed to an action that would result in a very fast deformation, they simply don’t have the time to move around and reshape their form, so they resist. When approached gradually, the non-Newtonian fluid will act as expected. Quicksand is a natural example of this phenomenon. Here’s an in-depth further read, and a very entertaining video.
#1. Gladiator Spider Hunting
Most spiders spend their time weaving great networks of webs to trap any unfortunate visitor. Rather than take the passive approach, the gladiator spider has inverted the process and leads a rather active hunting life. It carefully weaves a quadratic net, which is very elastic, and although not very sticky, it does well to entangle whiskers, bristles, and hairs. When it’s ready, the gladiator spider waits for the perfect moment. Its eyes are very developed and allow it to spot prey in near darkness. After it’s close enough, the spider pounces downward while extending the net, trapping the insect. Watch the full video here.