Why do two eye give better vision than one ?

Because two eyes do not form exactly similar images and the fusion of these two dissimilar images in the brain gives three dimensions of the stereoscopic vision.


Posted by : Vishal.Kalgutkar

Why is it dangerous to sleep under a tree at night ?

Plants respire at night and give out carbon dioxide which reduces the oxygen content of air required for breathing




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How does ink get filled in a fountain pen ?

When the rubber tube of a fountain pen is immersed in ink is pressed, the air inside the tube comes out and when the pressure is released the ink rushes in to fill the air space in the tube.




Posted by : Vishal.Kalgutkar

Why are ventilator in a room always made near the roof ?

The hot air being lighter in weight tends to rise above and escape from the ventilator at the top. This allows the cool air to come in the room to take its place.




Posted by : Vishal.Kalgutkar

Why do we place a wet cloth on the forehead of a patient suffering from high temperature ?

Because of body’s temperature, water evaporating from the wet cloth produces a cooling effect and brings the temperature down.




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Why cannot a petrol fire be extinguished by water ?

Water, which is heavier than petrol, slips down permitting the petrol to rise to the surface and continue to burn. Besides , the existing tempature is so high that the water poured on the fire evaporates even before it can extinguish the fire. The latter is true if a small quantity of water is poured.




Posted by : Vishal.Kalgutkar

Who will possibly learn swimming faster – A fat person or a thin person?

The fat person displaces more water which will help him float much more freely compared to thin person.




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Why are winter nights and summer nights warmer during cloudy weather than when cloud is clear.

Cloud is a bad conductor of heat and hence does not permit heat radiation from land to escape into the sky. As the heat remains in atmosphere, the cloudy nights are warmer.




Posted by : Vishal.Kalgutkar

Why is it difficult to breath at higher altitude ?

Because of lower air pressure at higher altitudes the quantity of air is less, and so also that of oxygen.




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Why is the water in an open pond cool even on a hot summer day ?

As the water evaporates from the surface of the pond, heat is taken away in the process, leaving the surface cool.




Posted by : Vishal.Kalgutkar

Why does ice float on water ?

The weight of ice block is equal to the weight of the liquid displaced by the immersed portion of the ice.




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Why is it that a small ball of iron sink in water but a large ship floats ?

The weight of water displaced by an iron ball is less than its own weight, whereas water displaced by the immersed portion of a ship is equal to its weight.




Posted by : Vishal.Kalgutkar

Why does an electric bulb explode when it is broken?

The bulb has partial vacuum and as it breaks, air rushes in causing a small explosion.




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Why does the electric filament in a electric bulb burn up ?

Because it is made up of tungsten which has a very high melting point (3410 C) whereas the temperature of the filament required to glow is only 2700 C . Secondly, the oxygen is absent since the bulb is filled with an inert gas which does not support burning.




Posted by : Vishal.Kalgutkar

Why is a rainbow seen after a shower ?

After a shower the clouds containing water droplets act like a prism through which the white light is dispersed producing spectrum. 

Why is the water from a hand pump warm in winter and cold in summer ?

In winter the outside temperature is lower than that of water flowing out of the pump, and therefore , the water feels warm. Whereas in summer, the outside temperature is higher than the water of the pump, and therefore, it feels cold.

Why does ice float on water but sink in alcohol ?

Because ice is lighter than water it floats on water. However, ice is heavier than alcohol and hence sinks in water.




Posted by : Vishal.Kalgutkar

Why do we perspire on a hot day ?

When the body temperature rises, the sweat glands are stimulated to secrete perspiration. It is the nature’s way to keep the body cool. During the process of evaporation of body sweat, body heat is taken away, thus , giving a sense of cooling.




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When a man fires a gun, he is pushed back slightly ?

As the bullet leaves the nozzle of the gun’s barrel with momentum in a forward direction, as per the Newton’s third law of Motion, the ejection imparts to the gun equal momentum in a backward direction.




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If a feather, a wooden ball and a steel ball fall simultaneously in a vacuum, which one of this will fall faster?

All will fall at the same speed in a vacuum because there will be no air pressure and earth’s gravitional force may exert similar force on all the objects.




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Why do stars twinkle ?

  

The light from a star reaches us after refraction as it passes through various layers of air. When the light passes through the earth atmosphere, it is made to flicker by the hot and cold ripples of air and it appears as if stars are twinkling.




Posted by : Vishal.Kalgutkar