When a leech bite causes continuous blood flow, some put paper ash. Leeches secrete an enzyme called hirudin which inhibits blood clotting. As paper ash is basic, it reacts with hirudin and disrupt its task.
Shortsightedness is the difficulty to see distant objects clearly.The reason is light reflected from distant objects are focused infront of the retina(not on the retina). Cornea(outer section of the eye) and the eye lens do the job of converging light. As the refractive index of the cornea and water are similar, the cornea doesn’t refract light effectively. This reduces the convergence, making light focus on the retina. So, they see far away lands under water!
If you are shortsighted you must have noticed that you can see distance better when you are underwater. Why does shortsightedness get cured when you are underwater?
As you know, bats learn about their surroundings by emitting sounds, and analyzing the returning sound. But did you know that humans have that ability too? This is a hidden talent discovered by blind people. As they rely on hearing so much, they develop super hearing powers. As, brain regions associated with vision become active when experts use this technique, it is a good substitution for vision.
Did you know that hollow paddy grains can be separated from good paddy grains by using water? When put in water, hollow grains float and good grains sink. Can you remember the physics lesson which explains this? It is the Archimedes’ principle of floatation. If the weight of an object is greater than the weight of a fluid with the same volume, it sinks. If not the object floats. As hollow grains can displace a volume of liquid equal to their weight, they float.
Most believe that brown eggs are more nutritious than white eggs. But, you should not judge an egg by it’s shell! Studies have shown that both egg types have the same nutritional value. As long as both hens get the same food, the nutritional value would be the same. So, why should we buy more expensive brown eggs?
When a wet cloth is drying, water absorbs heat and evaporates (endothermic reaction). As rocks are rough and dark in colour they are good at absorbing sunlight. So, apart from getting heat from sunlight, the cloth absorbs heat from the rock as well and dries quickly. But as grass doesn’t get hot and keeps it’s cool, the cloth gets less heat. In addition, grass gives out water vapour by transpiration(If you lay a transparent polythene on the grass,you’ll see water droplets form after a while), making the cloth a bit wet again.
A wet cloth dries faster when laid on a rock than when laid on grass. Can you explain this?
Let’s be aware of some flood safety tips.You should turn off utilities at the main switches and evacuate homes in danger of flood risk,be careful of damaged bridges,builidngs and power lines and avoid drinking unclean water.You should not touch wet electrical equipment. Do not drive into flooded areas. If flood waters rise around your vehicle, abandon it and move to higher ground if you can do so safely.
Have you heard that sometimes frogs or even fish fall from the sky when it rains? How did those flightless animals end up in the sky? It happens when a tornado(we got familiar with tornadoes on a previous day) moves through a lake/water body( known as a tornadic waterspout). Sometimes, tornadic waterspouts lift animals on it’s path. Strong winds carry them miles away and let go, making animals rain.
How wonderful would it be if we could generate electricity from a paddyfield! It is done by a plant-microbial fuel cell. Micro-organisms decompose organic material (secreted by plant roots) and release electrons and protons as waste. These cells gather those and generate electricity. Currently, these cells are used in some buildings to produce electricity but scientists say that even paddyfields should be equipped.
When lightning hits the ground (e.g. a tall tree), current flows through the earth around the point of impact. As we know, current flows between two points when there is a potential difference. As you go further away from a point in the path of the current, the potential difference between the two points increase. The distance between the front and back legs of a cow is considerably higher than that of a human’s. So, as there is a considerably higher potential difference between a cow’s legs, a current flows through it. As the resistance of the cow is constant, the higher the potential difference, the larger the current.
If lightning strikes in an open field with cows and humans, cows are in greater danger of getting hit indirectly by that lightning strike, than humans. Do you know the reason for this?
Humans are now addicted to plastic but, scientists are trying to change that. They have come up with a plastic-free material to wrap fruits. This wrap is made from an edible protein in silk called fibroin. This extremely thin (almost invisible) wrap has been able to keep fruits fresh for more than a week because it reduces respiration.
Recently, our country had experienced an unfamiliar disaster called “tornado. Do you know how these form? Sometimes during a thunderstorm, when warm air rises, cool, dense air or air with a different speed blocks the hot air. Then the hot air forms a horizontal cylinder and spin. As more warm air combines with the cylinder, it creates a greater upward force and straightens up. When the air column combines with a thunder cloud a disastrous tornado is born.
An amazing natural solution to clean up unfortunate oil spills in oceans is provided by milkweed plants. The fibers of the seed pods of this plant are hydrophobic (they repel water) and also great at absorbing oil (lipophilic). So, clean-up kits have been made from these fibers to absorb oil efficiently. These are already in use in Canada to clean small oil spills.
Even though the bottle looks empty to the eye, it’s not. It’s filled with air. As the temperature of hot water is higher than the air, heat transfers from hot water to air. As the process occurs in a closed system at constant pressure, the increased temperature in air causes the air to expand(Its volume increases). This inflates the balloon. But, the exact opposite happens when put in cold water. The air releases heat and gets contracted, making the balloon deflate.
If you cover a glass bottle’s opening with a balloon and put it in a bowl of hot water, the balloon expands. If you put that bottle in a bowl of cold water the balloon would shrink. Do you know the reason for this?
How do some people lay on a bed of nails and not get hurt? Do they have super powers? Actually, it’s not as deadly as it looks. If a person sat on one nail it would be painful but having lots of nails close together is the trick! These nails make a bigger surface area for the weight of the person to spread. So, the pressure applied from the nails on the person is less, making it less painful. As these are performed by professionals, don’t try it at home!
When you stretch an elastic band it gets thinner in the middle.But, an ‘adaptive protein crystal’ does something strange! When stretched in one direction, the material thickens in the perpendicular direction and when squeezed, it shrinks in the perpendicular direction.It gets these unique abilities from its flexible bonds which rotate its proteins.This would make armour which strengthens when a bullet strikes.
Did you know that dolphins can recognize specific individual’s calls up to 25 kilometres away? They have found a way to avoid the scattering of their high frequency sound waves by using sound waves with several frequencies in each transmission. This has inspired the idea of a sensor which reports underwater earthquakes. It is currently being used throughout the Indian Ocean, to guard lives from tsunamis.
Objects in rotational motion(these have rotational kinetic energy) tend to keep rotating(It is called rotational inertia). So, the fan blades tend to keep rotating but,air resistance and the friction caused by fan parts deduct the rotational kinetic energy. The reason is that the above factors produce a torque(an influence for a rotation) in the opposite direction to the rotation of the blades.If the torque wasn’t present the fan blades would keep rotating forever!