L. 4. Pressure in Fluids

Size: px

Start display at page:

Download "L. 4. Pressure in Fluids"

Daniel Russell
6 years ago
Views:

1 PHYSICS Std-IX SECTION A [20 X 2 =40] L. 4. Pressure in Fluids 01. Define the term thrust. State it s S.I Unit. 02. What is meant by pressure? State its S.I Unit. 03. What physical quantity is measured in bar? How is the unit related to the S.I unit Pascal? 04. It is easier to cut with a sharp knife than with a blunt one. Why? 05. Why do sea divers need special protective suit? 06. Why does the nose start bleeding, if one travels in a non-pressurized aero plane? 07. Why does fountain pen leak on higher attitudes? 08. Define one Pascal (Pa). 09. State three factors on which the pressure at a point in a liquid depends. 10. Write down the formula for pressure at any point in a liquid and explain the various symbols used. 11. Why is the water tank in a locality always at a higher altitude than the buildings in the locality? 12. Why are special suits needed by the astronauts while floating in space? 13. Bodies of deep sea fishes burst, if brought to sea level. Explain. 14. State two advantages of aneroid barometer. 15. State Pascal s law of transmission of pressure in a liquid. 16. P is the pressure at some point in a liquid state, whether P is a scalar or vector quantity. 17. Define atmosphere pressure. 18. What do you understand by the term Torricelian Vaccum 19. Why is barometric pressure expressed in terms of centimeters of mercury rather than in Pascal? 20. Give two uses of barometer. 21. Explain, Why a gas bubble released at the bottom of a lake grows in size as if rises to the surface of the lake.

2 L.5 Upthrust and Archimedes Principle 22. What do you understand by the term buoyant force or upthrust? 23. State Archimedes principle. 24. A person can lift a very heavy stone immersed in water easily as compared to in air. Why? 25. The volume of floating ice above brine solution is higher as compared to that in fresh water. Why? 26. The fish weighs less in water than in air. Why? 27. Define relative density. 28. Why is the relative density of the substance known as pure number? 29. What do you understand by the centre of buoyancy? 30. State the law of floatation. 31. What do you understand by the term meta-centre? 32. What is a hydrometer? State the principle on which hydrometer is based? 33. Why it is easier to swim in sea-water than in river-water? 34. State the necessary condition required by a floating body. L-7. Transmission of Heat 35. What do you understand by the term conduction as applied to heat? 36. What are good conductor?, Give two examples. 37. Name three solid conductors and one liquid conductor. 38. Why are metals good conductors of heat? 39. Why are non-metals and organic substances bad conductor? 40. What are Insulators? Name any two insulators. 41. What do you understand by the term convection? 42. Why does the land become warmer than water during the day? 43. How is motor car engine cooled? 44. You are sitting around a camp fire. Name the mode of transmission of heat due to which you feel warm. Why do not other modes of transmission of heat play any significant role? 45. Name four properties of radiant heat. 46. Why do people wear white clothes in summer and dark clothes in winter? 47. Why are the cooking utensil blackened from the base and kept shining from the sides? 48. Why are the cooking pans provided with plastic or wooden handles? 49. Why do the birds puff up their feathers in winter? 50. Define radiant heat energy. 51. In summer, If an wooden chair and an iron chair both are kept in sun; and are touched, the iron chair appears to be warmer than the wooden chair why? 52. A newly made quilt is warmer than an old one. Why?

3 53. Is it possible to heat a liquid or gas from above? Explain your answer. 54. Heat is received from a source only by the process of radiation. How is the medium in between the two, affected? Lesson-08 Light 55. What do you understand by the term light? 56. What do you understand by the term lateral inversion? 57. A printed card has letters PHYSICS. By drawing the diagram show the appearance of the letters when held in front of a plane mirror. 58. State the mirror formula for the formation of total number of images formed in two plane mirrors, held at an angle. 59. State four characteristics of the image formed in a plane mirror. 60. Draw a neat two ray diagram to illustrate how a concave mirror is used as a shaving mirror. 61. Give two uses of convex mirror. 62. Give two uses of concave mirror. 63. Why does a driver use a convex mirror as a rearview mirror? 64. Give two ray diagram for an image of an extended object. 65. Name four surfaces where regular reflection can take place. 66. Draw a diagram to verify the laws of reflection. 67. State two differences between real and virtual image. 68. State the laws of reflection. 69. What should be an angle between two mirrors to get 5 images? 70. Draw a ray diagram for a concave mirror when the object is at infinity, but the rays coming from it are not parallel to principal axis. 71. Why concave mirror acts as a converging mirror? 72. Parallel rays are incident on regular surface and on irregular surface. In what respect do the reflected rays in both differ? Lesson-09 Sound 73. What do you understand by the term sound energy? 74. Give two examples for comparing sound waves and light waves. 75. State the range of sonic vibrations for the human ear. 76. How do bats locate their prey during flight? 77. What is Galton s whistle? 78. Why do astronauts talk to each other through radio telephone in space? 79. Why material waves are also known as elastic waves? 80. State the factors on which the wave-velocity of sound depends?

4 81. Explain- The frequency of a sound is 500 Hz. 82. Give two examples of material waves. 83. How does a bat avoid obstacles in its way when in flight? waves pass through a point in one second. Calculate the time-period of wave. 85. What do you understand by the term ultrasonic vibrations? L-11 Electricity and Magnetism Define electric potential. 87. How many electrons pass through a conductor if a charge of one coulomb passes through it? 88. State and define S.I. unit of potential difference. 89. What do you understand by quantity of charge? 90. Define one coulomb. 91. Define the term potential difference. 92. How is potential difference related to work done and quantity of charge? 93. Name two electric conductors and two electric insulators. 94. What do you understand by resistance of material? 95. Draw a diagram showing two bulbs connected in series to a dry cell. 96. Draw a diagram showing two bulbs connected in parallel to a dry cell. 97. What do you understand by rheostat? 98. What is a resistance box? 99. Differentiate between a cell and a battery What is a galvanometer? 101. Why do we use an ammeter? 102. Differentiate between A.C. Generator and a D.C. Generator What is a voltmeter? 104. What do you understand by plug key? With the help of a diagram show an open plug key and a closed plug key Differentiate between insulators conductor related to electricity A charge of 8860 C flows through an electric circuit in 2 min and 40 s. Calculate the magnitude of current in circuit A dry cell can supply a charge of 800 C. If continuous current of 8.0 ma is drawn, calculate the time in which cell will discharge completely. Lesson-13-Energy flow and practices for conservation of resources 108. Name two renewable and the two non-renewable sources of energy State the law of conservation of energy State two limitations of wind energy.

5 111. Define kinetic energy. Give two examples of it What do you mean by renewable source of energy? Give two examples State two traditional uses of solar energy State the full-form of CNG and LPG What do you mean by dissipated energy? 116. Why it is advisable to use biogas over biomass? 117. Name a device which directly converts solar energy to electric energy. Name an agent which decomposes animal dung into biogas State two main reasons for using biogas as a fuel What is a solar panel? 120. Define potential energy. Give two examples of it. SECTION-B 6X10=60 Lesson 4. Pressure in Fluids 1. (a)derive the expression for P=h.l.g (a) State the laws of liquid pressure. (b) Calculate the pressure exerted by 75cm of vertical length of water column in SI units. (Take g= 9.8m/s 2 ) 2. (a) Derive the mathematical expression for MA of hydraulic press. (b) Give three uses of hydraulic press. (c) 0.96m vertical height of liquid exerts pressure of Pa. If g is 9.8m/s 2, calculate the density of the liquid. 3. (a) Why is mercury used as a barometric liquid? (b) Determine an equivalent height, if water is used as a barometric liquid. Also explain why it is not used as a barometric liquid. (c) Calculate the equivalent height of a water barometer, if the pressure recorded by the barometer is 60cm of mercury. Density of mercury is 13600kg/m 3 and density of water is 1000kg/m 3 L.5 Upthrust and Archimedes Principle 4. (a) Derive mathematical expression for upthrust. (b) State the characteristics of floating body. (c) A solid of density 1600 kg/m 3 is found to weigh 0.40 kgf in air. If 5/8 volume of solid is completely immersed in brine solution of density 1200 kg/m 3,find the apparent weight of solid in brine.[g=10 N/kg]

6 5. (a) Derive mathematical expression for the Law of floatation. (b) Explain the three types of equilibrium for floating body. (c) An iron cube of side 5 cm and of R.D. 7.6 is suspended by a thread in brine solution of relative density Find the tension in thread. L-7. Transmission of Heat 6. (a) Explain conduction in solids on the basis of (i) Kinetic model (ii) Electron model (b) Prove by an experiment that water is poor conductor of heat. (c) The pressure in water pipe at the ground floor of a building is Pa, whereas the pressure on the third floor is 30000Pa. Calculate the height of third floor. Take g=10m/s 2 7. (a) Name four properties of radiant heat. Support each with Illustration (b) Draw a neat diagram of thermos flask and state clearly how heat loses by thee modes are minimized. (c) A hydraulic press is used to lift a load of 500kgf when the ratio of the diameters of pump plunger and press plunger is 1:5. Calculate the effort applied on the piston of pump plunger. If the mechanical advantage of the handle of pump plunger is 4, calculate the effort applied on the handle of the pump plunger. 8. (a) Describe formation of sea-breeze with suitable diagram. (b) Explain the principle of natural ventilation. Why ventilators are made near the top (c) Calculate pressure exerted by 0.8m vertical length of alcohol of density 0.80g/cm 3 in SI unit. Take g= 10m/s 2 Lesson-08 Light 9.a) By drawing a neat diagram define the following:- (i) Reflected ray (ii) Angle of incidence (iii) Mirror b) Draw a ray diagram for magnifying glass. Also give its characteristics. c) A boy stands 5m away from plane mirror. If the boy moves 1m towards the mirror what is now the distance between the boy and his image? Give a reason for your reason.

7 10. a) Prove experimentally that images are formed as far behind in a plane mirror as the object is in front of it. b) State the principle of simple periscope through an outline ray diagram. Give two of its uses. c) Calculate the number of images formed in two plane mirrors, when they are held at the angle of (i) 72 (ii) a) Define the term principal focus and focal length in case of convex mirror. Draw a convex mirror and show its principal focus and focal length clearly. b) (i) What is a real image? (ii) What type of mirror is used to obtain a real image of an object? (iii)does the mirror named by you above give real images for all locations of objects? Give reason for your answer. c) Draw ray diagram for concave mirror, when object is in between the principal focus and centre of curvature. Also give its characteristics. Lesson-09 Sound 12.a) Explain the conditions necessary for hearing a sound. b) State three practical applications of the ultrasound vibrations. c) The wavelength of red light is 6500 A. If velocity of light is 3x10 8 m/s, calculate (i) frequency (ii) time-period 13.a) State four differences between light waves and sound waves. b) Explain the characteristics of a medium for a propagation of sound. c) The distance between three consecutive crests of wave is 60cm. If the waves are produced at the rate of 180/min, calculate: wave-length (ii) time period (iii) wave velocity 14. a) Describe an experiment to prove that material medium is necessary for the propagation of sound.

8 b) Define the following terms and also give its SI unit:- (i) Time period (ii) Frequency (iii) wave velocity c) A sound wave of wavelength 1/3 m has a frequency 996Hz. Keeping the medium same if frequency changes to 1328Hz, calculate (i) velocity of sound (ii) new wavelength. L-11 Electricity and Magnetism a) What are the characteristics of resistance connected in parallel? (b) What do you understand by the term electric current? State its unit and also give its multiple and sub-multiple. (c) Calculate the total number of number of electrons flowing through a circuit in 20 mins and 40s, if a current of 40 ua flows through the circuit. 16. (a) How does electric current flow in (i) solids (ii) liquids? (b) What do you mean by electric cell. Explain two types of electric cell with an example. (c) A charge of 5 coulombs is moved into an electric field from infinity, when the work done at point A is 20 J and at point B is 32 J. Calculate the potential difference between points A and B. 17. (a) Define e.m.f of cell. State the factors on which it depends. (b) What are the characteristics of resistances connected in series? (c) A block of wood of length 50 cm and area of cross-section 10 cm 2, floats in water with 3/5 of its length above water. Calculate: (i) Density of wood (ii)weight of wood (iii)extra force required to completely submerge it in water. Lesson a) State four uses of solar cell. b) State the limitations in harnessing solar energy. c) Calculate (i) wavelength (ii) time period of a tuning fork of frequency 480Hz which is set to vibrate. Take velocity of sound in air 332m/s. 19. a) State two advantages and two limitations of hydel power.

9 b) State three ways by which you can enhance the collection of solar energy. c) A block of wood floats in brine solution of density 1.20 g/cm3, such that 3/8 th of its volume is above brine. Calculate the density of wood. 20. a) Explain the energy changes taking place in a hydroelectric dam. b) State the energy conversions in the following cases: (i) microphone (ii) steam engine (iii) washing machine c) A block of wood floats in water with 3/10 of its length above water. If the block is made to float in salt solution of R.D 1.05, find what fraction of its length is above salt solution.

PHYSICS. SCIENCE Paper 1. (Two hours) You will not be allowed to write during the first 15 minutes.

PHYSICS. SCIENCE Paper 1. (Two hours) You will not be allowed to write during the first 15 minutes. CLASS IX PHYSICS SCIENCE Paper 1 (Two hours) Answers to this Paper must be written on the paper provided separately. You will not be allowed to write during the first 15 minutes. This time is to be spent