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question_answer1) Define thrust. Give its SI unit.
question_answer2) State a condition for an object to float when placed on the surface of water.
question_answer3) Why do we prefer a sharp knife for cutting than a blunt one?
question_answer4) What are the two forces acting on a body floating in a liquid?
question_answer5) When a floating body is pressed down a little, which force will increase at that time?
question_answer6) Which of the two will double the pressure? Doubling the area or making the area half.
question_answer7) What are the factors which affect the buoyant force?
question_answer8) Why do needles have sharp edge?
question_answer9) State buoyancy.
question_answer10) Give the uses of (a) Lactometer (b) Hydrometer.
question_answer11) A bucket of water weighs less inside the well water. Why?
question_answer12) What is relative density?
question_answer13) Find the force acting on an area of 0.5 m2 will produce a pressure of 50 Pa.
question_answer14) Find the mass of 5 m3 of cement of density 3000 kg/m3.
question_answer15) If the density of a body is 800 kg/m3. Will it sink or float when dipped in a bucket of water? [Density of water =1000 kg/m3]
question_answer16) There are four balls A, B, C and D which displace 10 mL, 24 mL, 15 mL and 12 mL of a liquid respectively, when immersed completely. Which ball will undergo the maximum apparent loss in weight?
question_answer17) Four measuring cylinders with different least counts are shown in figure A, B, C and D. Which of the following cylinders is the most suitable cylinder for determining the volume of a cube of side nearly 1cm?
question_answer18) If the relative densities of four liquids P, Q, R and S are 1.26, 1.0, 0.84 and 13.6 respectively. An object is floated in all these liquids in succession. In which liquid, the object will float with its maximum volume submerged under the liquid?
question_answer19) Find the weight of the object from the following diagram.
question_answer20) A student takes the following observations for finding out the volume of a given body. Find the volume.
question_answer21) If 100 cc of water is at 20°C, at what temperature its density will be maximum?
question_answer22) Density of glass is 3.5 g/cm3. What does it mean?
question_answer23) Four students have taken readings to verify Archimedes' principle. Which of the following students has taken the correct reading? Wt. of the object in air Wt. lost by the object Buoyant force Wt. of the water displaced Student 1 100 N 30 N 70 N 30 N Student 2 100 N 30 N 30 N 70 N Student 3 80 N 30 N 30 N 30 N Student 4 80 N 30 N 50 N 50 N
question_answer24) During an experiment, on measurement of loss in weight of solid in tap water and salty water, when will be the maximum loss in weight of the solid observed?
question_answer25) A force of 30 N is applied on a nail whose tip has an area of cross-section of 0.001 cm2. Find the pressure on the tip.
question_answer26) What are the least counts of (a) the spring balance and (b) measuring cylinder?
question_answer27) The spring balance shown in the following diagram is used to measure the weight of a given solid. What is the weight of solid?
question_answer28) While determining the density of the material of metallic sphere using a spring balance and measuring cylinder. Ruby noted the following readings (a) Mass of the sphere = 81 g (b)(i) Reading of water level in the cylinder without sphere = 59 mL (ii) Reading of water level in the cylinder with sphere = 68 mL On the basis of these observations, find the density of the material of the sphere.
question_answer29) Ishita noted down the following observations in her notebook. (a) Weight of the stone in air =280 gwt (b) Weight of the stone in water = 240 gwt (c) Weight of the stone in salty water = 190 gwt (d) Find the relative density of salty water.
question_answer30) Name two forces which act on a body immersed in a liquid. Give the directions in which they act.
question_answer31) Give one example each where the same force acting on (a) a smaller area exerts a larger pressure. (b) a larger area exerts a smaller pressure.
question_answer32) A solid body of mass 150 g and volume 250 cm3 is placed in ajar containing water. Will it float or sink in water? [Density of water is 1 g/cm3.]
question_answer33) Write two applications of Archimedes' principle.
question_answer34) Name the force experienced in a fluid. What is the direction of this force?
question_answer35) Why does a nail sink in water but a piece of cork floats on it?
question_answer36) When you immerse an empty plastic bottle in a bucket of water, it comes above the surface of water. Why does this happen? How can it remain immersed in water and why?
question_answer37) Which of the two will exert more pressure; 80 kg mass on 10 m2 or 40 kg mass on 4m2?
question_answer38) If two forces in the ratio 5 : 9 act on two areas in the ratio 10 : 3, find the ratio of pressure exerted.
question_answer39) The relative density of silver is 10.8. The density of water is 103 kg/m3. What is the density of silver in SI unit?
question_answer40) Why should we keep the base of dams broader?
question_answer41) State the law of floatation.
question_answer42) (a) Write down an equation which defines density. (b) If a 4 kg of material A occupy 20 cm3 and 18 kg of material B occupy 90 cm3. Which has the greater density A or B? Support your answer with calculations.
question_answer43) (a) Distinguish thrust and pressure. (b) Why is it easier to swim in sea-water than in river water?
question_answer44) (a) State the SI units of thrust and pressure. (b) In which situation, we exert more pressure on ground when we stand on one foot or on the both feet? Justify your answer.
question_answer45) While passing nearby a pond, some students saw a drowning man screaming for help. They alerted another passerby, who immediately threw an inflated rubber tube in the pond. The man was saved. Respond to the given questions using the information provided above (a) Why the passerby did use inflated rubber tube to save the drowning man? (b) Write the principle involved here. (c) Which qualities shown by the students and the passerby do you identify that helped in saving the drowning man?
question_answer46) You received an e-mail from a friend living in a coastal town. He shared an experience with you that recently happened. While swimming on the coastline of the sea in common swimming attire, he thought of going deeper inside the sea. He was asked to abstain from delving deeper into the sea by the rescue personnel. Respond to the following questions using the information provided above (a) Why the rescue personnel asked your friend not to swim deeper inside the sea? (b) What values were exhibited by the rescue personnel?
question_answer47) Two different bodies are completely immersed in water and undergo the same loss in weight. Is it necessary that their weights in air should also be the same? Justify your answer.
question_answer48) Raju distributed milk in a society. The residents were complaining that milk was not pure. Raju claimed that he always brought pure milk. Sunita tested the milk with the help of a device. Milk was found impure and had water mixed in it. Everybody thanked Sunita. Read the given passage and answer the following questions (a) By which device, Sunita tested the purity of milk? (b) On what principle is this device based? (c) Throw the light on the values of Sunita.
question_answer49) When a fresh egg is put into a beaker filled with water, it sinks in water. But when a lot of salt was dissolved in the water, the egg begins to rise and then floats. Why?
question_answer50) During the summer vacations, Rohit visited his native village. He observed that for washing clothes, villagers used the water from the well. Out of curiosity, he drew water from the well and observed that the bucket of water appeared to be heavier as it came out of the water. Read the above passage and answer the following questions. (a)Name the principle used in the above passage. (b) Why bucket appears to be heavier in air? (c) Which values are reflected in Rohit's behaviour?
question_answer51) Explain the applications of Archimedes' principle.
question_answer52) What are the factors affecting buoyant force?
question_answer53) Shashank placed an iron cuboid of dimensions 4 cm x 7 cm x 10 cm on a tray containing fine sand. He placed the cuboid in such a way that it was made to lie on the sand with its faces of dimensions (i) 4 cmx 7 cm, (ii) 7 cm x 10 cm, (iii) 4 cmx 10 cm. If the density of iron is nearly 8 g/cm3 and . g=10m/s2, find the minimum and maximum pressure as calculated by Shashank.
question_answer54) What is up thrust? State two factors on which the magnitude of buoyant force acting on an object immersed in liquid depends. When a partially immersed body is pressed down a little, what will happen to the up thrust?
question_answer55) (a) When a golf ball is lowered into a measuring cylinder containing water, the water level rises by 40 cm3 when the ball is completely submerged. If the mass of ball in air is 44 g, calculate its density. (b) A kg sheet of tin sinks in water but if the same sheet is converted into a boat or a box, it floats. Give reason.
question_answer56) (a) A cube of side 5 cm is immersed in water and then in saturated salt solution. In which case will it experience a greater buoyant force. If each side of the cube is reduced to 4 cm and then immersed in water, what will be the effect on the buoyant force experienced by the cube as compared to the first case for water. Give reason for each case. (b) A ball weighing 4 kg and of density 4000 kg/m3 is completely immersed in water of density 103 kg/m3. Find the force of buoyancy on it. [Given, g =10 ms-2 ]
question_answer57) With the help of an example show that a body loses its weight when immersed in a liquid.
question_answer58) Saloni and Ishita went to beach for a walk. Saloni was wearing flat shoes, while Ishita wore high heeled shoes. Ishita was facing problem in walking in such shoes. Saloni held her hand so that she did not fall. Later, Ishita bought flat shoes and they both went back to the beach. Now, both are comfortable in walking in such shoes. Read the above passage and answer the given questions (a) Why could Ishita not walk on beach easily? (b) How did flat shoes help Saloni walk easily? (c)What are the values of Saloni?
question_answer59) What is a fluid?
question_answer60) What is specific gravity of a substance?
question_answer61) What do you mean by buoyancy?
question_answer62) What do you mean by buoyant force?
question_answer63) In what direction does the buoyant force on an object immersed in a liquid act?
question_answer64) What is the SI unit of buoyant force?
question_answer65) When an object is immersed in a fluid, name the two forces acting on it.
question_answer66) Why does an egg sink in freshwater but floats in highly salty water?
question_answer67) What is the relative density of silver?
question_answer68) What is the density of silver, given that its relative density is 10.5?
question_answer69) A body is fully immersed in water to a depth of 2m, 4 m and then 5 m, in turn. Will the loss in its weight be equal or different in three cases? If different, in which case will it be least?
question_answer70) The volume of a body of mass 50 g is 20 cm3. If the density of water is taken as 1 gcm-3, will the substance float or sink in water? Why?
question_answer71) What do you mean by thrust?
question_answer72) make use of the concept of pressure.
question_answer73) What are the factors which affect the pressure at a point in liquid?
question_answer74) Why is it difficult to hold a school bag having a strap made of a thin and a strong string?
question_answer75) State the laws of floatation.
question_answer76) Why does a camel walk easily on sand but it is difficult for a man to walk on sand though a camel is much heavier than a man?
question_answer77) State the laws of liquid pressure.
question_answer78) State the factors on which buoyant force depends.
question_answer79) Give any three applications of Archimedes' principle.
question_answer80) How is a submarine able to move on as well as go under water?
question_answer81) Why does an object float or sink when placed over the surface of water?
question_answer82) You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?
question_answer83) You have a bag of cotton and an iron bar, each indicating a mass of 100 kg when measured on a weighing machine. In reality, one is heavier than other. Can you say which one is heavier and why?
question_answer84) Why does a block of plastic released under water come up to the surface of water?
question_answer85) A piece of ice is placed gently on the surface of water in a glass so that when the ice floats, the water comes up to the brim of the glass. What will happen to the level of water when the ice melts? Will it over flow?
question_answer86) In the above question, what will happen if instead of water the glass is filled with (a) a liquid denser than water. (b) a liquid lighter than water.
question_answer87) Loaded test-tube placed in pure milk sinks to a certain mark (M). Now some water is mixed with the milk. Will the test tube sink more or less? Explain.
question_answer88) (i) Give an application of density. (ii) What are its units?
question_answer89) During a period of hot weather, the atmospheric pressure on the pond in figure remains constant. Water evaporates from the pond, so that the depth h decreases. What will be the force of the air on the surface of the pond?
question_answer90) A man squeezes a pin between his thumb and finger, as shown in figure. The finger exerts a force of 84 N on the pinhead. The pinhead has an area of . Explain why the pin causes more pain in the man's thumb than in his finger.
question_answer91) (i) State and explain the experiment for verification of Archimedes' principle. (ii) Name the devices based on Archimedes' principle.
question_answer92) (a) Explain, with the help of an example the difference between the terms thrust and pressure. Which one of the two has same SI unit as that of Force? (ii) Consider a wooden block of mass 5 kg and dimensions 40 cm X 20 cm X 10 cm with its faces 20 cm X 10 cm and 40 cm X 20 cm kept on the table, in turn. In which case will the pressure exerted by the box on the table be more? Justify your answer by doing mathematical calculations.
question_answer93) (a) A cube of side 5 cm is immersed in water and then in saturated salt solution. In which case will it experience a greater buoyant force? If each side of the cube is reduced to 4 cm and then immersed in water, what will be the effect on the buoyant force experienced by the cube as compared to the first case for water. Give reason for each case. (b) A ball weighing 4 kg of density 4000 kg is completely immersed in water of density 10 kg . Find the force of buoyancy on it. (Given g = 10 .)
question_answer94) Why does a sharp knife cut better than a blunt knife?
question_answer95) Why is the tip of the needle sharp?
question_answer96) Why is the pressure on ground more when a man is walking than when he is standing?
question_answer97) Why is depression much more when a man stands on the cushion than when he lies down on it?
question_answer98) Why is it easier to walk on soft sand if we have flat shoes rather than shoes with sharp heels?
question_answer99) Why do snow shoes stop you from sinking into snow?
question_answer100) Why does a ship made of iron and steel float in water whereas a small piece of iron sinks in it?
question_answer101) A boy gets into a floating boat. What happens to the boat? (b)What happens to the weight of water displaced? What happens to the buoyant force on the boat?
question_answer102) Why does the driver wear metallic cover while going into the sea?
question_answer103) Why are the walls of a dam made thick at the bottom and thin up wards?
question_answer104) Why is it easier to float in sea water than in river water?
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