Category Fun Facts

WHY DOES AN EXPANDING RUBBER BAND BECOME WARMER?

Try it with a rubber band. Stretch a rubber band and quickly hold it against your cheek. It feels warmer. Usually when things expand, a gas or liquid, for example, they become cooler.

When a liquid (or gas) expands, it takes the energy required for expansion from the liquid itself. So the liquid becomes cooler.

When a rubber band is stretched, it is not using up its internal energy. Energy is being supplied to it from the outside (by the one who is stretching it). So its internal energy increases and its temperature rises, making it slightly warmer to the touch.

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WHEN WE SHAKE SOFT DRINK VERY FAST THEN THAT COMES OUT WITH THE PRESSURE FROM THE BOTTLE. WHY IS THIS HAPPEN?

Do you enjoy an aerated soft drink? Have you noticed that the content fizzes and gushes out when you open the cap?

If I take a soft drink bottle from the fridge and open it after shaking it vigorously, the liquid spurts out. Why does it come out so forcefully after shaking?

If the liquid rushes out when a softdrink bottle is opened, it is because carbon dioxide is escaping from the water in the drink.

Carbon dioxide is introduced into the water at high pressure and cold temperatures. Besides causing the liquid to bubble when opened, a little of the carbon dioxide reacts with water to form carbonic acid which gives the drink its refreshing tangy taste.

If you shake a bottle vigorously before opening it, some of the gas in the head of the bottle above the liquid will get dissolved in the liquid. This gas is more than the water in the drink can normally dissolve and so when the bottle is opened the sudden release of pressure will cause the gas to rush out. This will bring the liquid out in a gush.

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WHY DO EARS POP IN A PLANE?

The popping sensation in the ears is caused by the effect of the changes in pressure and altitude. The most important part of the ear is the eardrum, a thin membrane separating the outer ear from the middle ear. Equal air pressure is maintained on both sides of the membrane by the Eustachian tube, a tube which connects the ear and the throat. Sudden changes in the air pressure like when going up or down in an aeroplane stretches the eardrum, causing discomfort. The Eustachian tube tries to normalise the pressure by forcing more air into the ear internally through. yawning or swallowing. This adjustment creates the popping sound which indicates that the air pressure is back to normal in the ear. Ears may pop even when you travel in a high speed elevator of a tall building or go scuba diving.

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WHY THE MOST OFTEN MEDICINES ARE STORED IN BROWN COLOURED BOTTLES?

Medicines normally contain different chemicals. These chemicals are photo-sensitive, that is, exposure to light and heat affects them. In fact, the composition of these medicines might change so much that they become ineffective. This is why the bottles are made of dark brown or opaque glass to minimise entry of light and heat if you look at the label there is a line that reads, ‘Store in a cool and dark place away from direct sunlight.

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WHY PENCIL MARKS ARE EASIER TO RUB OFF IF THEY HAVE BEEN RECENTLY MADE, AND HARDER TO ERASE IF THEY ARE A FEW DAYS OLD?

The pencil mark is made up of graphite particles. It is easy to erase when it is freshly, made because the graphite has not had time to penetrate into the tiny hollows of the paper.

The pencil mark also contains some wax. When the wax is fresh it seeps into the paper taking some particles of graphite along with it. When the wax hardens the graphite is fixed firmly onto the paper, and then it is not as easy to erase the mark as it was when it was freshly made.

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SOMETIMES WHEN WE UNWRAP OUR BAR OF CHOCOLATE IT HAS A WHITISH SURFACE. WHY?

In hot climates, chocolates tend to spoil fast and should be transported in refrigerated trucks. Usually, however, they are transported in ordinary vans. When chocolate that has melted during transportation is refrigerated, a white powdery layer called Fat Bloom forms on its surface due to migration of fat from the interior of the bar to the surface where it re-crystallises. As a result, the chocolate gets a whitish coat and does not taste as it should.

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