1.Why the planets are generally sphere in shape?
The force of gravitation appears to act generally from the center of the large mass like planets. To hold the mass together the spread of the gravitational force across the surface must be similar. This is possible only when the shape is round. That is why the most of the planets are spherical in shape. From the point at the center the distance to any corner of the planet is similar. They may not be perfect sphere as they appear.
2. Why certain part of the world is much cooler? And other is hot?
The earth tilted on its axis is about 23.5 degrees. It is not perpendicular. Since the earth’s axis is tilted, the sun is higher when we are on the part of the earth where the axis points more towards the sun (hotter), and lower on the part of the Earth where the axis points away from the Sun (cooler).
3. What does traveling in the night faster than day time?
The other reason than the general reasons like more traffic etc during day time, it is the climate during day and night that contributes to the velocity of the vehicle. Since day time is being hot, the upper layer of the bitumen is subjected to extreme heat conditions and hence melts making the surface soft which result in creating lesser friction for the tyres. During nights this layer gradually becomes tough in the absence of heat from the sunlight providing a tough layer to produce more friction and hence the vehicle travels faster.
4. Why traveling by plane looks very slow and by car looks faster?
It is because the distance of the vehicle above the ground and the area covered by the eyes. When we travel by plane our eyes covers a huge area due to the height which is not possible while on the ground. If you can watch aero planes landing the speed look to be faster even though the speed of the plane while landing is at minimum during the entire course of the journey.
5. There are 5 birds on the branch.3 decided to fly. How many remained?
There is a lot of difference between actually flying and deciding to fly. The action here is not completed when you just decide to fly. So the tree branch still has 5 birds on it! When they actually fly, 2 birds will remain.
6. Why the sky looks blue in color?
A clear cloudless day-time, sky is blue because molecules in the air scatter blue light from the sun. When the air is clear the sunset will appear yellow, because the light from the sun has passed a long distance through air and some of the blue light has been scattered away further. As we know the atmosphere contains dust particles and water droplets (moisture).It acts like a prism to the white sunrays and rays splits (Diffraction of light). As you look closer to the horizon, the sky appears much paler in colour because blue light is scattered away further as distance grows bigger and light has to pass through more air. Also the colours have different wavelengths, frequencies, and energies. Blue is scattered more than other colours because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.
7. How the traffic camera works or strikes at set speed limits?
The traffic camera at the road side pole continuously emits radio waves of a set definite frequency and positioned to hit the speeding vehicles. As we know the vehicles (cars) coming and approaching the camera pole have different speed levels say 100km, 114km, 118km and 120km etc. Even though the radio waves frequency coming out from the camera pole is equal to all vehicles, its returning frequency after hitting the vehicle is depending on the speed of the vehicle. Hence cars speeding with different speed, the returning radio wave frequency are different depending on the speed of the car (vehicle). The camera flash is adjusted in such a way that only the frequency coming from the car having speed limit exceeding more than 120km / hr (or any other set speed limit )is caught and below that is ignored. All this mechanism happens in a fraction of second!
8. Name the similarities between the Bird and an Aeroplane.
Observational Quiz—As all of us know planes were invented copying the bird since we wanted to fly like a bird. The similarities are
(1).Its shape-Wings, cockpit and fuselage
(2). Bird position its legs close to the body while taking off and flying.Similarely tyres of the aero plane is hidden inside the body after taking off and lowered during landing.
(3).The plane wings are adjustable according to the demands during taking off (to accelerate) and landing (to lower the speed and brake).
(4). Birds have blood in their body and aero plane has hydraulic fluid.
(5). Both use their wings to change the direction they fly (by changing the pressure).
9. What happens when car gears are shifted from 1, 2, 3 and 4?
As we all know vehicles have gears to operate. When a car is on neutral gear, its wheels are free and there is no fuel consumption. When you start the vehicle you push the gear to 1st gear and the car starting accelerating. In this position of the car, wheels are not much free and fuel consumption is more. As you go on shifting the gears from 1, 2 3 and 4 etc the velocity of the car increases as you press accelerator, wheels become more and more free and fuel consumption goes down. At the highest gear car wheels are freer and less the fuel consumption and the car (vehicle) speed steadily.
10. How the clouds are formed and rains?
Clouds are made of tiny drops of water that settle on dust particles in the atmosphere. There is water around us all the time in the form of tiny particles, also known as water vapour(When the sun heats water in the oceans, rivers, lakes and other sources, some of it evaporates and become water vapour). Clouds will be composed depending on the height of the cloud and the temperature of the atmosphere. As the air rises above the ground due to temperature it collects dust particles and tiny droplets in the air. The water vapour and the dust particles are constantly colliding into each other resulting in the formation of clouds.
Since warm air can hold more water than cool air, when the warmer air is cooled the moisture condenses to liquid – and it rains because it can no more sustain in air and gravitation brings it down and it rains.
11. What are Black Holes and why they are called so?
A black hole is a region in the space from which gravity prevents anything, including light from escaping. As all of us know to see something, the light has to fall on the surface and reflected light has to enter the retina of our eyes. The massive gravitational force present in the black holes makes the light impossible to escape and hence it is non visible. Its size and mass varies and sometimes it is much larger than that of the Sun. Black holes are made when the canter of a very big star falls in upon itself, or collapses. When this happens, it causes a supernova. A supernova is an exploding star that blasts part of the star into space.
12. Why dead body floats on water?
When the human body sinks in water, the air in the lung is replaced by water. As the body starts decaying due to bacterial activity, produces gas like hydrogen sulphide, methane etc. and makes the body floats on water. That is why the part of the body which produces more gas can be seen first on the water.
13. What is the meaning of the writing V6 / V8, I4 etc on the back of the car?
The writing indicates the number of cylinders mounted in the car engine. They are mounted either Longitudinal or Transverse style. V6 writing says that there are 6 cylinders in the car mounted in V shape, 3 cylinders on each side. Similarly a V8 indicates that there are 8 cylinders mounted in V shape, 4 each on either side.
14. What is the significance of ‘pixel’ in camera?
pixel is the basic element of the picture. It implies clarity of the picture. More the pixel, more the clarity and hence resembles closely with the original. Pixels are used to store colour information. Information in pixel is used to store in Bits.
Generally 5 mega pixel cameras are sufficient to yield better quality picture. One million pixels are called a mega pixel.
15. What does it mean by EMU HALT written on railway tracks in India?
An electric multiple unit or EMU is a multiple unit train consisting of self-propelled carriages, using electricity as the power. EMU Halt refers to the limit of their operating territory.
16. Why do earthquakes happens?
Earthquakes are usually caused when rock underground suddenly moves along a fault (a fracture accompanied by displacement of one side against the other). This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little. They don’t just slide smoothly; the rocks catch on each other. The rocks are still pushing against each other, but not moving. After a while, the rocks break because of all the pressure that’s built up. When the rocks break, the earthquake occurs. During the earthquake and afterward, the plates or blocks of rock start moving, and they continue to move until they get stuck again. The spot underground where the rock breaks is called the focus of the earthquake. The place right above the focus (on top of the ground) is called the epicentre of the earthquake.
17. What is the diff between a virus and bacteria?
Viruses are considered parasites because they cannot “survive” without a living cell. Viruses only have one purpose or goal: to multiply. Viruses don’t do anything good for the organism host. Bacteria, on the other hand, can do bad things for the body, like cause disease, and they can do good things for the body, like help make vitamins, depending on what type of bacteria they are.
2. A virus isn’t a cell (No cells; not living); Viruses are the smallest and simplest life form known. They are 10 to 100 times smaller than bacteria. The biggest difference between viruses and bacteria is that viruses must have a living host – like a plant or animal – to multiply, while most bacteria can grow on non-living surfaces. And doesn’t have any cellular parts. A virus has no internal cellular structure, no cell wall, or cell membrane. Viruses consist only of a protein coat that holds a coiled string of nucleic acid. Bacteria, on the other hand, are singled-celled (unicellular) organisms.
18. How cyanide kills instantly?
Cyanide blocks the oxidation of glucose inside a cell. This makes the iron atom unavailable to carry oxygen atom to the tissues through haemoglobin. Thus, cyanide brings an abrupt end to cellular respiration by reducing oxygen.
If the quantity consumed is below the lethal dose sodium nitrate and sodium thiosulphate may be used to treat cyanide poisoning.The average fatal dose is only 50 or 60 milligram.
19. What is SPF stand for in a sun cream?
SPF stands for Sun Protection Factor. And refers to the theoretical amount of time you can stay in the sun without getting sunburned. For example, an SPF of 15 would allow you to stay in the sun 15 times longer than you could without protection. So, if your skin starts to redden in 20 minutes without sun block, applying a product with SPF15 increases that time by a factor of 15, meaning you could stay in the sun for 300 minutes.
Always check the SPF range mentioned on the sunscreen package. Anything above SPF 15 is considered decent protection. But if you want fool-proof protection, go for a sunscreen offering SPF 30 or above as these products provide the best protection against Sun’s UV rays. It’s also important to know that SPF only applies to UVB rays. There is no SPF equivalent for UVA.
20. Why finger prints are used for identification?
Basically due to two features: their persistence and their uniqueness. A person’s fingerprints do not change over time. The friction ridges which create fingerprints are formed while inside the womb and grow proportionally as the baby grows. Permanent scarring is the only way a fingerprint can change. In addition, fingerprints are unique to an individual.
Even identical twins have different fingerprints. The chances of any two individuals sharing the same fingerprints are very rare or almost ruled out. Therefore the presentation of fingerprints at a scene or location is a strong indication of persons presence and used a s a solid evidence.
21. How DNA helps in investigation?
Almost every cell in our bodies contains DNA, the genetic material that programs how cells work. Any two people share, on average, 99.9% of their DNA, meaning that only 0.1% of your DNA is unique to you! The only exception is identical twins, who share 100% of their DNA.
Each human cell contains three billion DNA base pairs. Our unique DNA, 0.1% of 3 billion, amounts to 3 million base pairs. That’s more than enough to provide a profile that accurately identifies a person. Our body’s cells each contain a complete sample of our DNA. Passed through the sperm and egg to the offspring.
22. Why is mercury used in thermometers?
Most metals are good conductors of heat and they are solids at room temperature. Mercury is the only one in liquid state at room temperature. It’s used in thermometers because it has high coefficient of expansion.
Hence, the slightest change in temperature is notable when it’s used in a thermometer. It also has a high boiling point which makes it very suitable to measure higher temperatures. Also, it has a shiny appearance and doesn’t stick to the glass surface of glass.