What if you could simply throw on a cloak and disappear from sight just like Harry Potter does? ‘Invisibility Cloak’ has made this ridiculously feasible in the world of science fiction. Metamaterials made of metallic and dielectric films have given clues to make this possible even in our real lives! This cloak is known to have tiny structures smaller than wavelength of visible light. If properly arrayed, they guide light rays around the object, much like a rock diverting water in a stream. So that we won’t be able to visualize the object.
When water level in the filter is decreasing, hydrostatic pressure exerted on the bottom too decreases. When the tank is filled to the top since the potential energy of water is high, kinetic energy of the flowing water is also increased. While height of the water column gets lowered, force exerted on its bottom is also decreased. Then just like Bernoulli’s principle says kinetic energy stored in a unit volume of water coming out is lowered as well. Which means we see that speed of water flowing out of the tap has decreased.
Nowadays most of us get drinking water from our home water filters. So have you noticed when the water level in its water tank has considerably decreased, the speed of the water flowing out of the tap at the bottom too decreases? Explain the reason for this.
As humans we use simple tools to make our day to day work easier. But did you know that sea otters have been using tools before modern humans even existed? They collect rocks from the ocean floor, which they then balance on their bellies and use to break open clams and marine snails to get at the tasty meat within. Not only that otters are known to have favourite stones and they even store these best found tools under their arms for later use!
Have you heard of periosteum, the layer covering our bone tissue that protects bones from minor fractures and helps for its regeneration? Complex combination of structural proteins in this membrane gives bones extra strength under high impacts. Now for the first time, researchers have mimicked their architecture and smart stress-strain properties on fabrics, using silk and elastic materials in place of proteins. Taking this as the initiative step in weaving biological tissues, we could use them even to replace and repair our failing joints in future!
How long can you hold your breath for? 10 seconds, 30 seconds? Perhaps a minute? Emperor penguins can hold their breath for an amazing 20 minutes! When they dive under the ice in cold oceans, their heart rate slows to three beats per minute. This means blood moves round penguin’s body very slowly, minimizing the oxygen consumption. Also as they have loads more ultrasensitive hemoglobin than we do, they can carry lots more oxygen. Indeed it’s a blessing for them when finding preys in deep ocean.
Either day or night stars keep on emitting light. But during the day time as the bright sunlight enters the atmosphere and get scattered, sky appears in bright blue colour. Intensity of light rays from other far away stars are negligible when compared to the brightness of this atmosphere. So we cannot recognize them in day time.
During night we can see many stars glowing in the sky. But why can’t we see these stars in the day time, like we do at night?
You already know that sloths are renowned for being slow moving. Yet can you believe that sloths move so slowly that even algae grows on their fur? Instead of washing these algae away, sloths use it to feed their young ones. It also doubles up as an effective green camouflage for the tree-dwelling creatures.
Humans have used water to generate energy for literally thousands of years. What if we could do the same thing with flowing blood? Can you believe that Chinese scientists have developed a device to do just that! They’ve created a tiny fiber thinner than a hair, called “fluidic nanogenerator fiber” that generates electricity simply from the movement of blood. Their tests on frogs have been successful. If upcoming experiments go well, it’s possible that in the future you’ll discover that the power you need was in you all along.
Ice means cold solid water. When touching these, the heat from our fingers slightly melts the surface of ice cubes in contact. But as the fresh ice cubes are sufficiently cold (less than 0°C), moisture in our finger tips and water that was melted initially re-freezes quickly. So the ice freezes itself onto your skin making it seem sticky. Formation of hydrogen bonds between the ice structure and liquid water molecules is responsible for this process.
You’ve probably noticed that when taking frosty cold ice cubes from the ice tray, our fingers tend to stick to the ice. Why is ice sticky, especially when we touch it with wet hands?
How amazing it would be if our garments could change color in response to heat or pressure! Inspired by a tropical fruit called Margaritaria nobilis, scientists have cleared a path to create a new kind of fiber that changes color as it stretches. Distinctive blue color of this fruit is found to be caused by optical interference of light interacting with a highly complex nanostructure. By combining this structure with an elastic material, it would be able to create a smart fabric that passes through a full rainbow of colors as it’s stretched.
Weren’t you ever annoyed by your feline friend who keeps on scratching household furniture? You might be surprised to learn that there is a very specific reason behind this behavior. Cat paws have scent glands that can leave smells. So when scratching things, using these glands they leave behind smells for other cats and animals. Those smells let every feline in the area know that furniture is theirs! Also by doing this cats are getting rid of their old, worn-down nails so that they can grow new ones.
Has your stomach ever started growling so loud that it seemed like it wanted to ask “When is lunch?” But do you know why our stomach groans like this when hungry? Muscle contractions of the digestive system mix and propel food, gas and fluids along the digestive tract making a slight rumbling noise. Even when stomach is empty, these muscles keep on working to clean up any food that was missed earlier. But now as the digestive tube is empty and hollow, noises made by those gas and air pockets are made lot more loud and noticeable that we hear as stomach growling.
Normally we sneeze to clear our nasal passage when it is disturbed by the entry of an irritant. ‘Aaah’ part of the sneeze is the result of the massive inhalation at the beginning. When exhaling, pressurized air from the lungs escapes in a burst. During this as the tongue pushes against the roof of the mouth, air makes a ‘ch’ sound. Finally when the air column leaves the oral cavity through the narrow hole of the pursed lips an ‘oo….’ sound is produced.
When sneezing we naturally make that ‘AtChoo’ sound or similar noises. What makes us vocalize our sneezes like this?
You might have heard of producing large fruits and vegetables using genetic engineering to cure world hunger. Isn’t it amazing that researchers have found another way to do this, not with mutated genes but with the use of nanoparticles! Spraying zinc oxide and titanium dioxide nanoparticles to tomato plants has proved to boost their nutrient content and growth, by increasing the ability to absorb light and minerals. Directly depositing nanoparticles on leaves has resulted in a much greater uptake of nutrients than adding them to soil.
When newborn humpback whales are in trouble they call out their mother whales, just like we do. But did you know that to keep predators from eavesdropping, these babies and their mamas don’t use their outside voices? Instead they whisper! They’ve adopted whispering as a clever survival technique to avoid predators such as killer whales. It also avoid attracting attention of male humpbacks that might be looking for a mate, since they could interfere with crucial mothering time.
To maintain the balance, we need to have our line of gravity (imaginary vertical line drawn from a person’s center of gravity to the surface he is on) between our feet. When walking on an inclined plane this line lies perpendicular to the plane. So we have to lean forward and bend the body to keep our feet straight below the center of gravity. Otherwise feet would be in front of the center of gravity and we would topple over to the back. Similarly when going downhill, we have to lean downwards to avoid toppling over to the front.