0
question_answer1) We can cut an apple easily with a sharp knife as compared to with a blunt knife. Explain why?
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_answer8) Why is a slight blow on a cork of bottle filled with a liquid sufficient to break the bottle?
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_answer12) Why the food is cooked faster in the pressure cooker? Why it becomes difficult to cook food at the mountains?
question_answer13) Why the passengers are advised to remove the ink from their pens while going up in an aeroplane?
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_answer16) If a drop of water vapour is introduced in a mercury barometer, how will the barometric height change?
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_answer23) A beaker containing a liquid is kept inside a big closed jar. If the air inside the jar is continuously pumped out, how will the pressure change inside the liquid near the bottom?
question_answer24) Why does a siphon fail to work in vacuum?
question_answer25) A barometer kept in an elevator accelerating upwards reads 76 cm of Hg. What will be the possible air pressure inside the elevator?
question_answer26) A barometer accelerating downwards reads 76 cm of Hg. What will be the possible air pressure inside the jar?
question_answer27) In a mercury barometer, at sea level, the normal pressure of the air (one atmosphere) acting on the mercury in the dish supports a 76 cm column of mercury in a closed tube. If you go up in the air, until the density has fallen to half its sea level value, what height of mercury column would you expect?
question_answer28) A liquid cannot withstand a shear stress. How does this imply that the surface of a liquid at rest must be level, i.e. normal to the gravitational force?
question_answer29) A wooden block is on the bottom of a tank when water is poured in. The contact between the block and the tank is so good that no water gets between, them. Is there a buoyant force on the block?
question_answer30) A piece of iron sinks in water, but a ship made of iron floats in water. Why?
question_answer31) A man is sitting in a boat, which is floating in a pond. If the man drinks some water from the pond, will the level of water in the pond fall?
question_answer32) An ice cube floats in a glass of water filled to the brim. What happens when the ice melts?
question_answer33) An ice piece with an air bubble in it is floating in a vessel containing water. What will happen to the level of water when the ice melts completely?
question_answer34) Ice floats in water with about nine-tenths of its volume submerged. What is the fractional volume submerged for an iceberg floating on a fresh water lake of a (hypothetical) planet whose gravity is ten times that of earth?
question_answer35) Does the Archimedes' principle hold in a vessel in free fall?
question_answer36) What is the fractional volume submerged of an ice cube in a pail of water placed in an enclosure which is falling freely under gravity?
question_answer37) A piece of cork is floating in water contained in a beaker. What is the apparent weight of the cork piece?
question_answer38) One small and one big piece of cork are pushed below the surface of water. Which has greater tendency to rise swiftly?
question_answer39) Why is it easier to swim in sea water than in river water?
question_answer40) Two bodies of equal weight and volume and having the same shape, except that one has an opening at the bottom and the other is sealed, are immersed to the same depth in water. Is less work required to immerse one than the other? If so, which one and why?
question_answer41) A wooden cylinder floats in a vessel with its axis vertical. How will the level of water in the vessel change if the cylinder floats with its axis horizontal?
question_answer42) A block of ice is floating in a liquid of specific gravity 1.2 contained in a beaker. When the ice melts completely will the level in the beaker change?
question_answer43) A boy is carrying a fish in one hand and a bucket full of water in the other hand. He then places the fish in the bucket and thinks that in accordance with Archimedes' principle he is now carrying less weight as weight of fish will reduce due to up thrust. Is he right?
question_answer44) A solid body floats on mercury with a part of its volume below the surface. Will the fractional volume of the body immersed in mercury increase or decrease, if a layer of water poured on the top of mercury covers the body completely?
question_answer45) A bucket of water is suspended from a spring balance. Does the reading of balance change (a) When a piece of stone suspended from a string is immersed in water without touching the bucket? (b) When a piece of iron or cork is put in water in the bucket?
question_answer46) Why a sinking ship often turns over as it becomes immersed in water ?
question_answer47) A soft plastic bag weighs the same when empty as when filled with air at atmospheric pressure. Why?
question_answer48) Stirred liquid comes to rest after son time. Why?
question_answer49) What is the reason that a constant driving force is always required for the maintenance of the flow of oil through the pipe lines in the oil refineries?
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_answer54) One flask contains glycerine and other contains water. Both are stirred vigorously and kept on the table. Which liquid will come rest to earlier than the other?
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_answer66) What happens when the velocity of a liquid becomes greater than its critical velocity?
question_answer67) What happens to the external energy maintaining the flow of a liquid when the flow becomes turbulent?
question_answer68) Why does the velocity increase when water flowing in a broader pipe enters a narrow pipe?
question_answer69) Why still water runs deep?
question_answer70) Why it is dangerous to stand near the edge of the platform when a fast train is crossing it?
question_answer71) Why two boats moving in parallel directions close to each other get attracted?
question_answer72) Why does the speed of a liquid increase and its pressure decrease, when the liquid passes through a narrow constriction in a pipe?
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_answer76) When air is blown between two balls suspended close to each other, they are attracts towards each other. 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_answer80) If air is blown very fast into the vertical hole of a spool of thread, a card laid flat against the other end does not fall. Why?
question_answer81) Explain why we cannot remove a filter paper from a funnel by blowing air into its narrow end.
question_answer82) According to Bernoulli's theorem, the pressure of water in a horizontal pipe of uniform diameter should remain constant. But actually it goes on decreasing with the increase in length of the pipe. Why?
question_answer83) What is the effect on the equilibrium of a physical balance when air is blown below one pan?
question_answer84) In case of an emergency, a vacuum brake is used to stop the train. How does this brake work?
question_answer85) Is Bernoulli's theorem valid for viscous liquid?
question_answer86) Two cylindrical vessels placed on a horizontal table contain water and mercury respectively up to the same heights. There is a small hole in the walls of each of the vessels at half the height of liquids in the vessels. Find out the ratio of the velocities of efflux of water and mercury from the holes. Which of the two jets of liquid will fall at a greater distance on the table from the vessel? Relative density of mercury with respect to water\[=\text{ }\mathbf{13}.\mathbf{6}\].
question_answer87) If a small ping pong ball is placed in a vertical jet of water or air, it will rise to a certain height above the nozzle and stay at that level. Explain.
question_answer88) Bernoulli?s theorem holds for incompressible, non-viscous fluids. How is this relationship changed when the viscosity of the fluid is not negligible?
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_answer97) One can form a fairly large vertical film of soap solution but not of pure water. Why?
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_answer102) Oil spreads over the surface of water whereas water does not spread over the surface of oil. Why?
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_answer105) A needle floats on the surface of pure water but goes down when detergent is added to water. Why?
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_answer109) A oil drop on a hot cup of soup spreads over when the temperature of the soup falls. Why?
question_answer110) Glass marbles are made by heating the end of a glass rod until drops of molten glass fall. Explain.
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_answer116) Why are the droplets of mercury when brought in contact pulled together to from a bigger drop? Also state with reason whether the temperature of bigger drop will be the same, or more, or less than the temperature of the smaller drops?
question_answer117) The angle of contact for a solid and a liquid is less than\[\mathbf{90}{}^\circ \]. Will the liquid wet the solid? Will the liquid rise in the capillary made of that solid?
question_answer118) Write down formula for excess pressure inside (i) a liquid drop (ii) a soap bubble.
question_answer119) Why excess pressure in a soap bubble is twice the excess pressure of a liquid drop of the same radius?
question_answer120) Two soap bubbles of unequal sizes are blown at the ends of a capillary tube. Which one will grow at the expense of the other and what does it show?
question_answer121) What is the importance of (i) wetting agents used by dyers, and (ii) water proofing agents?
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_answer133) Water gets depressed in a glass tube whose inner surface is coated with wax. Why?
question_answer134) If a capillary tube is immersed at first in cold water and then in hot water, the height of capillary is smaller in the second case. Why?
question_answer135) If a capillary tube is put in water in a state of weightlessness how will the rise of water in a capillary tube be different to one observed under normal conditions?
question_answer136) How is the rise of liquid affected, if the top of the capillary tube is closed?
question_answer137) A 20 cm long capillary tube is dipped in water. The water rises up to 8 cm. If the entire arrangement is put in a freely falling elevator, what will be the length of water column in the capillary tube?
question_answer138) Spherical balls of radii R are falling in a viscous fluid of viscosity \[\eta \] with a velocity \[\upsilon \]. How does the retarding viscous force acting on a spherical ball depend on R and \[\upsilon \]?
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?
question_answer142) Problem 1. Explain why : (i) A balloon filled with helium does not rise in air indefinitely but halts after a certain height (Neglect winds). (ii) The force required by a man to raise his limbs immersed in water is smaller than the force for the same movement in air.
question_answer143) What height of water column produces the same pressure as a 760 mm high column of Hg?
question_answer144) A small ball of mass m and density \[\rho \] is dropped in a viscous liquid of density \[\rho \]. After some time, the ball falls with a constant velocity. Calculate the viscous force on the ball.
question_answer145) A tank filled with fresh water has hole in its bottom and water is flowing out of it. If the size of the hole is increased what will be the change in: (a) Volume of water flowing out per second? (b) Velocity of the out coming water? (c) If in the above tank, the fresh water is replaced by sea water, will the velocity of out coming water change?
question_answer146) In a bottle of narrow neck, water is poured with the help of an inclined glass rod. Why?
question_answer147) The excess pressure inside a soap bubble is thrice the excess pressure inside a second soap bubble. What is the ratio between the volume of the first and the second bubble?
question_answer148) The viscous force 'F' acting on a body of radius 'r' moving with a velocity ' \[\upsilon \]' in a medium of coefficient of viscosity ?\[\eta \]? is given by \[F=6\pi \eta r\upsilon \]. Check the correctness of the formula.
question_answer149) Two soap bubbles of different diameters are in contact with a certain portion common to both the bubbles. What will be the shape of the common boundary as seen from inside the smaller bubble? Support your answer with a neat diagram. Give reason for your answer.
question_answer150) A big size balloon of mass M is held stationary in air with the help of a small block of mass \[\mathbf{M}/\mathbf{2}\]tied to it by a light string such that both float in mid air. Describe the motion of the balloon and the block when the string is cut. Support your answer with calculations.
question_answer151) A tarnado consists of rapidly whirling air vortex. Why is the pressure always much lower in the centre than at the outside? How does this condition account for the destructive power of tarnado?
Please Wait you are being redirected....
You need to login to perform this action.You will be redirected in 3 sec
OTP has been sent to your mobile number and is valid for one hour
Your mobile number is verified.