question_answer2) Why are the bags and suitcases provided with broad handles?
question_answer3) Railway tracks are laid on large sized wooden sleepers. Why?
question_answer4) It is painful to walk barefooted on the ground covered with edged pebbles. Why?
question_answer5) It is difficult for a man to walk on sand. Why?
question_answer6) Water does not come out of a dropper unless its rubber bulb is pressed hard. Why?
question_answer7) Why two holes are made to empty an oil tin?
question_answer9) What is the force on a man due to atmospheric pressure? Why one does not feel it?
question_answer10) How does the boiling point of a liquid vary with pressure?
question_answer11) Why the boiling point of a liquid varies with pressure?
question_answer14) Why is it difficult to stop bleeding from a cut in human body at high altitudes?
question_answer15) Why are straws used to suck soft drinks?
question_answer17) Why water is not used in barometers?
question_answer18) Why is mercury used in barometers?
question_answer19) Why is the reading of a mercury barometer always less than actual pressure?
question_answer20) How can we check whether the barometric tube contains air or not?
question_answer21) The dams of water reservoir are made thick near the bottom. Why?
question_answer22) Why an air bubble in water rises from bottom to top and grows in size?
question_answer24) Why does a siphon fail to work in vacuum?
question_answer30) A piece of iron sinks in water, but a ship made of iron floats in water. Why?
question_answer35) Does the Archimedes' principle hold in a vessel in free fall?
question_answer39) Why is it easier to swim in sea water than in river water?
question_answer46) Why a sinking ship often turns over as it becomes immersed in water ?
question_answer48) Stirred liquid comes to rest after son time. Why?
question_answer50) What is the effect of temperature on the viscosity of liquids and gases?
question_answer51) Hotter liquids move faster than colder ones. Why?
question_answer52) Why oils of different viscosity are used in different seasons?
question_answer53) Why machine parts are jammed in the winter?
question_answer55) Why should the lubricant oil be of high viscosity?
question_answer56) Why does an object entering the earth's atmosphere at high velocity catch fire?
question_answer57) The velocity of water in a river is less the bank and large in the middle. Why?
question_answer58) Which fall faster - big rain drops or small rain drops?
question_answer59) Why rain drops falling under gravity do not gain very high velocity?
question_answer60) Why dust generally settles down in closed room?
question_answer61) Why do clouds seen floating in the sky?
question_answer62) Explain why parachute is invariably used, while jumping from an aeroplane.
question_answer63) Fog particles appear suspended in the atmosphere. Give reason.
question_answer64) The sides of a horizontal pipe carrying dirty water get dirty. Why?
question_answer65) Why two streamlines cannot cross each other?
question_answer69) Why still water runs deep?
question_answer71) Why two boats moving in parallel directions close to each other get attracted?
question_answer73) Why does a flag flutter, when strong winds are blowing on a certain day?
question_answer74) On which principle does a carburetor work?
question_answer75) Roofs of the huts are blown up during stormy days. Why?
question_answer77) An aeroplane runs for some distance the runway before taking off. Why?
question_answer78) The accumulation of snow on the aeroplane may reduce the lift. Explain.
question_answer79) Why bullets are given cylindrical shape?
question_answer85) Is Bernoulli's theorem valid for viscous liquid?
question_answer89) Why are the cars and aeroplanes given streamline shape?
question_answer90) Why a glass rod coated with wax does not become wet when dipped in water?
question_answer91) Mercury does not cling to glass. Why?
question_answer92) Why is it not possible to separate two pieces of paper joined by glue or gum?
question_answer93) Why does the free surface a liquid behave like an elastic stretched membrane?
question_answer94) Why does mercury collect itself into drops when placed on a clean glass plate?
question_answer95) How dental plate clinges to the roof of the mouth?
question_answer96) What shape does a liquid take when it weighs nothing?
question_answer98) Small insects can move about on the surface of water. Why?
question_answer99) Why ends of a glass tube become rounded on heating?
question_answer100) Antiseptics have low surface tension. Why?
question_answer101) Why hot soup tastes better than cold soup?
question_answer103) Why does a stream of water from a faucet become narrow as it falls?
question_answer104) Why do the hair of a shaving brush cling together when taking out of water?
question_answer106) Why it becomes easier to spray the water in which some soap is dissolved?
question_answer107) The clothes are better cleaned with hot water than with cold water. Why?
question_answer108) How does soap help us to remove dirt better in washing clothes?
question_answer111) Oil is sprinkled on sea waves to calm them. Why?
question_answer112) A tiny liquid drop is spherical but a larger drop has oval shape. Why?
question_answer113) Why does a small piece of camphor dance about on the water surface?
question_answer114) The addition of flux to tin mat soldering easy. Why?
question_answer115) The paints and lubricating oils have low surface tension. Why?
question_answer122) Teflon is coated on the surface of non-sticking pans. Why?
question_answer123) What makes water-proof rain coat water-proof?
question_answer124) How does the ploughing of fields help in preservation of moisture in the soil?
question_answer125) How does the cotton wick in an oil-filled lamp keep on burning?
question_answer126) Why sand is drier than clay?
question_answer127) Why undergarments are usually made of cotton?
question_answer128) A piece of chalk immersed in water emits bubbles in all directions. Why?
question_answer129) Why new earthen pots keep water cooler than the old one?
question_answer130) Why is the tip of the nib of a pen split?
question_answer131) Water rises in a capillary tube, whereas mercury falls in the same tube. Why?
question_answer132) Why is it difficult to make mercury enter a fine thermometer tube?
question_answer136) How is the rise of liquid affected, if the top of the capillary tube is closed?
question_answer139) Why do air bubbles in a liquid move in upward direction?
question_answer140) Explain why some oils spread on water, when others float as drops.
question_answer141) What happens when a capillary tube of insufficient length is dipped in a liquid?
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