We are an intelligent species that has always sought explanations for everything. We've explored the oceans and space and found answers to many complex questions. But our curiosity isn't, and shouldn't be, limited to complex things. Sometimes simple and mundane topics spark our curiosity, demanding an explanation. So, we've explained 12 random things you might always have wondered about.
1. Why do planes need to fly so high?
As the plane gains altitude, the air becomes thinner. This reduces drag, allowing the aircraft to fly more efficiently.
When experiencing turbulence during flight, you'd likely want the plane to fly lower, closer to the ground. While technically, planes can fly closer to the ground than usual, this will increase fuel consumption due to decreased fuel efficiency.
Here's how to do it:
The atmosphere thins as you rise above the ground. When an airplane flies in a thinner atmosphere, it experiences less drag from fewer air molecules. Less drag means less energy is required to move forward, which leads to less fuel consumption. This reduces fuel costs and, ultimately, airline operating expenses, helping them maximize profits. (source)
2. Why do sounds like nails scraping on a chalkboard, and even the imagination of them, cause such an unpleasant sensation?
One of the reasons why the sound of nails scraping on a chalkboard and other similar sounds is so irritating is that they trigger our body's fight-or-flight response. There's also a hypothesis that such irritating sounds resemble the calls of predators early in human evolution.
The sound of fingernails scraping against a chalkboard makes one want to pull out one's hair. Numerous studies have been conducted to pinpoint the cause of this spontaneous and uncontrollable reaction, and the scientific community has reached varying conclusions.
There are two conclusions that point to human evolution. First, such sounds trigger an emotional response in our bodies, which triggers the fight-or-flight response. This is our body's defense mechanism, developed over the course of evolution.
The second conclusion is that, in ancient times, early in human evolution, predators produced sounds similar to the scratching of our nails. Thus, we are programmed to respond in a similar way. (source)
3. Why do plastic containers never dry in the dishwasher?
The main reason plastic containers remain damp in the dishwasher is that, unlike ceramic or metal, plastic cools quickly. This prevents water droplets from evaporating.
Finding wet dishes when unloading the dishwasher is an unpleasant experience, and plastic cups and containers are usually the culprit. There are two reasons for this:
Firstly, plastic has low thermal inertia. This causes plastic items to cool faster, which slows the evaporation of residual moisture. As a result, the dishes become wet and slippery.
The second reason is the "low-energy bonds" of polypropylene, the most common plastic used in kitchenware. Water also has "low surface energy," which results in a uniform distribution of water across the plastic's surface. As a result, large water droplets form on plastic products, requiring more heat and time to evaporate. (1, 2)
4. How do fitness trackers know that you are actually sleeping and not just lying down and resting?
Fitness trackers use accelerometers to measure sleep. The sensor detects the wearer's movements and tracks the direction and speed of these movements. This data is then processed by a sophisticated algorithm developed by experts to determine whether the user was truly sleeping or simply resting.
Sleep tracking apps and devices have gained popularity because our modern lifestyles expose us to stress and anxiety. A good night's sleep is essential to counteract the effects of stress on our minds and bodies during the day.
To help us get a better night's sleep, many fitness trackers are equipped with sensors that monitor the quantity and quality of our sleep. While the ability of a simple sleep tracker to measure sleep quality is questionable and disputed by sleep scientists, it does a decent job of measuring the quantity and duration of a person's sleep.
To measure sleep duration, such devices must distinguish between when a person is truly asleep and when they are simply resting or lying awake. This is achieved by using a three-axis accelerometer, which tracks all the user's movements. The collected data is then analyzed using established sleep parameter algorithms to determine whether the person is actually sleeping or not. (1, 2)
5. Why do soda cans have two holes?
To make drinking even more enjoyable, the second hole on the soda can's pull tab is designed for attaching a straw. Simply flip and twist the pull tab to align the hole with the can's opening, and insert the straw through the holes.
The tongue of a soda can opener has two holes. The purpose of the larger hole is obvious: it serves as a stop for your finger when opening the can. The usefulness of the second hole is often discussed, but rarely addressed.
So, this often-ignored hole is there for ease of use. It's designed to keep the straw perfectly in place while drinking. Simply rotate the tag so the hole aligns with the hole in the can, then insert the straw through the hole into the can and drink. (source)
6. Why do videos from the 70s often look better than videos from the 90s when you watch them?
In the 1970s, video was recorded on analog film, which has a higher resolution than video recorded on magnetic tape and digital cameras in the 1990s.
Technology has advanced with each passing year, and we've come to expect better performance from gadgets in later periods of history. Therefore, it's somewhat alarming to see higher-quality video footage created in the 1970s compared to that shot in the 1990s.
Well, the videos from the 70s we find online were shot on analog film. Analog film has finer grain than pixels, resulting in crisp, high-resolution images.
Digital cameras emerged in the 1990s. Because the technology was still in its early stages, the quality of digital video and photos was not very high.
Furthermore, even today, film photographs are better at capturing the fine details that digital cameras are likely to miss. (source)