6 What is the sinking sensation we feel in the stomach while going downhill on a roller-coaster?

A common sensation people notice on roller-coasters is the sinking feeling in their stomachs when it suddenly drops. This is because when we fall freely during a downhill move, our internal organs and the fluids inside them slightly shift in position. As a result, we experience a sudden sinking feeling in our stomachs telling us something is not right. 

Roller-coaster rides are one of the most popular attractions in most amusement parks. A common experience associated with these rides is the distinct sinking sensation we feel in our guts when the roller-coaster makes a sudden drop. Although this feeling is something most of us have experienced, not all of us actually understand what causes it. 

What we feel in this situation is the sudden loss of force on our organs exerted by the ground beneath us. This force is spurred on by gravity and is what helps keep our organs in place.

When we experience freefall, like on a roller-coaster that suddenly drops, gravity and the ground no longer support our organs, causing them and their contents to shift inside our bodies. Since the intestines, unlike other organs, are not fixed in place by ligaments, we feel the sinking sensation more in our gut than anywhere else. (1, 2)

7 How do people have fires inside igloos without melting them? 

Although igloos are made completely out of snow, the Inuit people have always built fires inside them to keep warm. Surprisingly, this doesn’t melt down the igloo. This is because the atmosphere outside the igloo is so cold that even when the snow inside melts a little, it quickly solidifies again. 

Igloos are one of the most fascinating pieces of human architecture found on earth. Built completely from snow, they are used by the Inuit people to shelter themselves from the harsh weather. They are also known to build small fires inside the igloos to keep themselves warm. As a result, many people have wondered how this is possible without melting down the igloo. 

The fact is, yes, the fire will melt the insides of the igloo over time. However, if the fire is small enough and the weather is cold outside, this should not be a big problem.

This is because any little snow that does manage to melt from the fire will quickly freeze again because of the harsh cold outside the igloo. In fact, the melting and refreezing actually strengthens the igloo and allows it to be absolutely safe to light a fire inside it. (1, 2)

8 What makes “permanent” markers permanent?

Typically, “permanent” marker ink is made from a blend of pigment or dye, a resin, and an alcohol-based solvent. When the alcohol evaporates, the ink is left behind on paper with just a film of the resin on it. This way, the ink becomes less likely to fail and is more “permanent”. 

A permanent marker is typically defined as one that uses dyes or pigments, is water-resistant, and can adhere to surfaces for a sufficient period of time. To achieve this, the ink used in the marker has to be of a specific type. 

This ink is made from a colorant or pigment mixed in with a carrier like alcohol and a resin. Together, these things allow the pens to leave a “permanent” mark behind. 

The pigments used in these marker pens are strong dyes that do not fade easily. These are mixed in with a carrier that can evaporate quickly and leave just the pigment behind. 

Earlier, the carriers used were xylene and toluene, but these have been replaced by alcohols today. Finally, there is the resin that forms a film over the pigment, further protecting it from fading. When all these ingredients do their part, it allows the ink to remain on a surface longer. (1, 2)

9 Why does water get louder as it gets hotter and quieter as it cools down? 

When water is heated, it often gets louder as the temperature rises. This is because when water gets hot, the gasses trapped in it rise to the surface as bubbles and pops on the surface. As a result, the water starts making more noise as more air bubbles escape at higher temperatures. 

If you have ever closely observed water that is being heated, it makes little to no noise until it is about to start boiling. Then, as it cools down, it becomes quieter and quieter until no more noise is heard. Therefore, the loudness of water increases with temperature and is the loudest just before it starts boiling. Let’s look at why this happens.

There are numerous gasses that are found partially dissolved in water. When the water’s temperature increases, their solubility reduces and they form bubbles at the bottom levels of the vessel. As the temperature continues to rise, these bubbles move towards the surface, all the while exerting huge amounts of energy on the surrounding molecules.

This then makes the water whistle softly even without the formation of steam. Finally, once the bubbles reach the surface, they burst with a loud pop, causing the sounds typically associated with boiling. (1, 2) 

10 What causes the distinct smell in the air after it rains? 

The distinct smell that comes after a rain is called “petrichor.” This “rain” smell is actually caused by a bacteria called Actinomycetes which produces its spores when the soil is dry. Later, when the raindrops fall on the soil, these spores are kicked into the air and give out the smell. 

After a light shower of rain, there is a distinct smell in the air that we’ve all come to love. This smell, called “petrichor,” has long been of interest to scientists and perfume companies for its enduring appeal.

It turns out, this warm, earthy fragrance is the handiwork of an order of bacteria called Actinomycetales. Of these, Streptomyces bacteria are one of the most common types that produce the smell. 

These microorganisms produce a chemical called “geosmin” in their spores that is responsible for giving out this smell. During light showers, the spores and the chemical form aerosols and spread the smell far and wide in the air. This then allows us to detect it more easily.  

Geosmin can also seep into groundwater supplies and underground crops like beetroots, giving them an earthy flavor. Surprisingly, as much as we enjoy smelling the compound, most people find that it tastes unsavory. (1, 2)