SOUND - PART II

SPEED OF SOUND IN DIFFERENT MEDIA

74. Sound of a thunder is heard ---------------- than the flash of light is seen.
75. The speed of sound is ---------------- the speed of light.
76. Temperature influences the speed of sound. True or False?
77. The speed of sound ---------------- when we go from solid to gaseous state.
78. In any medium, as we increase the temperature the speed of sound increases. True or False? Give example.
79. Go through the table 12.1.

REFLECTION OF SOUND

80. Sound gets reflected at the surface of a solid and liquid. True or False?
81. What is normally needed for the reflection of the sound waves?
82. Learn the activity related to reflection of sound and understand the process.

ECHO

83. What is called an echo?
84. The sensation of sound persists in our brain for about --------- s.
85. When could you hear a distinct echo? Explain in detail.
86. What is t
he relationship between echo and the rolling of thunder?

REVERBERATION

87. What is reverberation?
88. What are the steps to be taken to reduce reverberation?

USES OF MULTIPLE REFLECTION OF SOUND

89. How are the musical instruments designed to send sound?
90. How is the sound heard in the stethoscope?
93. How are the ceilings of the concert halls designed?

RANGE OF HEARING

94. The audible range of sound for human beings extends from about ------------ to ------------.
95. Children upto five years and dogs can hear upto ----------------.
96. How is the hearing affected as the human beings grow old?
97. What are called infrasound or infrasonic sound?
98. What is the infrasound of frequency used by rhinoceroses for communication?
99. How can some animals hear the sound of earth quake even before it occurs?
100. What are called ultra sound or ultrasonic sound?
101. Name the creatures that produce ultrasonic sound.

APPLICATIONS OF ULTRASOUND

102. How are ultrasounds used extensively in industries and for medical purposes?
103. How is ultrasound used for the purpose of cleaning?
104. How can ultrasounds be used to detect cracks and flaws in metal blocks?
105. What is called echocardiography / ECG?
106. Describe the functioning and uses of ultrasonic scanner.
107. What is called ultrasonography?
108. What is the use of utltrasound in the breaking and removal of kidney stones?

SONAR

109. Expand SONAR.
110. What is sonar?
111. How does the sonar work? Explain in detail.
112. What is called echo-ranging?
113. What are the uses of sonar?
114. How do bats locate food in the dark?
115. Why do porpoises use ultrasound?

STRUCTURE OF HUMAN EAR

116. Describe in detail the auditory aspect of human ear.
117. What is pinna?
118. What is the function of pinna?
119. What is the function of the middle ear?
120. What is cochlea? What is its function?

SOUND - PART I

INTRODUCTION

1. What is sound?

PRODUCTION OF SOUND

2. Can you produce sound without a vibrating object? Explain with example.
3. Give examples of some actions that produce sound.
4. What is vibration?
5. How is human voice produced?

Go through activities 12.1 and 12.2.

PROPAGATION OF SOUND

6. How is sound produced?
7. What is called a medium?
8. The medium can be -----------, ---------------- and ---------------.
9. Describe the process of formation of sound and how it it is heard by us.
10. What is a wave?
11. How do the waves influence the sound?
12. How can be sound visualised as a wave?
13. What are mechanical waves? Why are they called so?
14. ----------- is the most common medium through which wound travels.
15. What is called compression?
16. What is called rarefaction?
17. Compression is the region of ----------------.
18. Rarefaction is the region of ----------------.
19. Pressure is related to the ----------------- of a medium in a given volume.
20. Propagation of sound can be visualised as ---------------------------- or ------------------------ in the medium.

SOUND NEEDS A MEDIUM TO TRAVEL

21. Sound cannot travel through ----------------------.
22. Explain with an experiment, the necessity of a medium for the sound to travel.

SOUND WAVES ARE LONGITUDINAL WAVES

23. What are longitudinal waves?
24. Why are sound waves longitudinal waves?
25. How do the particles of the medium move in the longitudinal wave?
26. What is a transverse wave?
27. What is the difference between the longitudinal and the transverse wave?
28. How do the particles move in the transverse wave?
29. Light is a ------------- wave.
30. Why is not a transverse wave a mechanical wave? Explain.

CHARACTERISTICS OF A SOUND WAVE

31. We can describe a sound wave by its ----------, --------------- and ----------------.
32. How does the density and pressure of the medium  vary at a given time?
33. Compressions are the regions where particles are -----------------------------.
34. Compressions are represented by the ------------------- of the curve.
35. The peak represents the region of ---------------------------.
36. Compressions are regions where -------------- and --------------  are high.
37. Rarefactions are the regions where particles are ----------------.
38. Rarefactions are represented by the ----------------- of the curve.
39. A peak is called the --------------- and a valley is called the ---------------.
40. What is called the wavelength?
41. How is the wavelength represented?
42. What is the SI unit of wavelength?
43. When sound is propagated through a medium, the density of the medium oscillates between ------------ and ---------------.
44. What makes one complete oscillation?
45. How can you get the frequency of the sound wave?
46. What is called the time period of the wave?
47. Time period is represented by the symbol ----------.
48. Its SI unit is -------------.
49. Frequency and time period are related as ---------------------.
50. Why is the sound produced by a violin and a flute played at the same time in an orchestra differ when we hear?
51. What is called the pitch?
52. How does the vibration affect the pitch?
53. What does high pitch sound correspond to?
54. How are diffferent pitch created?
55. What is called the amplitude of the wave?
56. It is represented by the letter -----------------.
57. What is the unit of amplitude?
58. ------------- and ------------- of a sound are determined by its amplitude.
59. What is the difference in the sound produced when we strike a table lightly and when we hit it harder? Why is it so?
60. Why can loud sound travel a larger distance?
61. A sound wave spreads from its -------------.
62. As the sound wave moves away from the source its -------------- and ---------------- decrease.
63. What is the quality or timber of sound?
64. What is the characteristic of the timber of sound?
65. What is a sound of rich quality?
66. What is called a tone?
67. What is a note?
68. What is the quality of noise? Why?
69. What is the quality of music? Why?
70. Practise the sums and questions given in page 166.
71. What is called the intensity of sound?
72.' Loudness' and 'Intensity' are same. True or False?
73. What is loudness?

WORK AND ENERGY

INTRODUCTION

1. What are 'life processes'?

WORK

2. What is work?

SCIENTIFIC CONCEPTION OF WORK

3. What are the conditions that need to be satisfied for work to be done?
4. If one of the two conditions does not exist, then work ---------------------.

WORK DONE BY A CONSTANT FORCE

5. Work done = -----------------------------------------------
6. W = -------------
7. Work has only ----------------- and no ------------.
8. Unit of work is -------------- or -------------.
9. Work done is ------------------ when the force acts opposite to the direction of displacement.
10. Work done is ---------------- when the force is in the direction of displacement.
11. Define 1J of work.
12. Explain some situations in which force and the displacement are in the same direction.
13. Explain some situations in which force and displacement are in the opposite direction.

ENERGY

14. ----------------- is the biggest natural source of energy to us.
15. We can also get energy from other natural resources like --------------, --------------- and ---------------------.
16. What is energy?
17. An object capable of doing work is said to possess -----------------.
18. The object which does the work ------------------ energy.
19. The object on which the work is done --------------- energy.
20. How does an object with energy do work?
21. Unit of energy is ---------------.
22. Why is the unit of energy same as the unit of work?
23. What is name of the larger unit of energy?
24.  1 kJ = ----------------.

FORMS OF ENERGY

25. What are the different types of energy?

KINETIC ENERGY

26. Define kinetic energy.
27. Derive the expression for kinetic energy of an object.

POTENTIAL ENERGY

28. Define potential energy.

GRAVITATIONAL POTENTIAL ENERGY

29. What is the gravitational potential energy?
30. Derive the expression for the gravitational potential energy.

LAW OF CONSERVATION OF ENERGY

32. Define the law of conservation of energy.
33. kinetic energy + potential energy = -----------------.
34. Explain the transformation of energy from one form to another form with a suitable example.
35. Explain the law of conservation of energy with an example.

RATE OF DOING WORK

36. Life is impossible without transformation of energy. Do you agree? Why?
37. What is Power?
38. Power = --------------------.
39. P = ---------------.
40. Unit of power is -------------.
41. What is watt?
42. 1 watt = ------------------------: 1 W = -------------------.
43. 1 kilowatt = ------------------
44. 1kW = ---------------.
45. 1kW = ------------------.
 46. Why is the concept of average power useful?
47. Average power = ----------------------.

COMMERCIAL UNIT OF ENERGY

48. An object of mass m moving with velocity v has a kinetic energy of --------------.
49. The energy used in one hour at the rate of 1KW is called ----------------.

THRUST AND PRESSURE, BUOYANCY, DENSITY ….PART II

32.      Define density.

33.      The density of cork is ------------ than the density of waqter.

34.      The upthrust of water on the cork is ------------------ than the weight of the cork.

35.      The density of an iron nail is ------------- than the density of water.

36.      The upthrust of water on the iron nail is ------------- than the weight of the nail.

37.      Why does an iron nail sink in water?

38.      Objects of density less than that of water -----------------  the liquid.

39.      Objects of density greater than that of water -------------- the liquid.

40.      (Stone string experiment) The elongation produced in the string or the spring balance is due to the --------------------------------.

41.  When the stone is immersed in water, some force acts on the stone in an ------------------ direction.

42.  What is known as the force of buoyancy?

43.  Define Archimedes’ Principle.

44.  Mention the fields / applications where Archimedes’ Principle is used.

45.  What is the unit of density?

46.  The density of a given substance under specified conditions -------------------------.

47.  Density is -------------------- for different substances.

48.  What is the density of gold?

49.  What is the density of water?

50.  The density of a given sample of a substance can help us to determine its -------------------

51.  .Relative density = ------------------------------- .

52.  It is convenient to express density of a substance in comparison with that of -----------------.

THRUST AND PRESSURE, BUOYANCY, DENSITY ….

  THRUST AND PRESSURE

1.      Why can a camel run in a desert easily?

2.      Why does an army truck rest upon a continuous chain?

3.      Why do trucks and motorbuses have wider tyres?

4.      Why do cutting tools have sharper edges?

5.      Why does a nail have a pointed tip?

6.      Why do buildings have wide foundation?

7.      It is difficult to hold a school bag with a thin strap or a string. Why?

8.      What is thrust?

9.      What is pressure?

10.  Explain the principles of thrust and pressure by giving suitable examples.

11.  The effects of forces of the same magnitude on different areas are -------------------- .

12.  The effect of thrust depends on the ------------------- .

13.  The effect of thrust on sand is ---------------- while standing than while ----------------- .

14.  The thrust on unit area is called ------------------ .

15.  Complete the following:

Pressure = ---------------

16.  SI unit of pressure is ------------- or -------------------.

17.  SI unit of pressure is called Pascal denoted as --------------, in honour of scientist --------------- .

18.  The same force acting on a smaller area exerts -------------------------.

19.  The same force acting on a larger area exerts -------------------------.

PRESSURE IN FLUIDS

20.  Fluids have weight and they exert pressure on the ------------ and wall of the container.

21.  Pressure exerted in any confined mass of fluid is --------------- ---------------------- in all directions.

BUOYANCY

22.  Why do you feel lighter in a swimming pool?

23.  While drawing water from a well the bucket is lighter when it is inside the water level and heavier when it is out..why?

24.  A ship made of iron and steel does not sink in water, whereas a sheet made of the same metals sink in water. Why?

25.  Define buoyancy.

26.  Explain buoyancy by doing an activity.

27.  Weight of an object is the ----------------- due to gravitational attraction of the earth.

28.  All objects experience ------------------------- when they are immersed in a fluid.

29.  The upward force exerted by the water on a given object is known as ---------------------- or -----------------------------.

30.  The magnitude of the buoyant force depends on the density of the fluid. True or False?

WHY OBJECTS FLOAT OR SINK WHEN PLACED ON THE SURFACE OF WATER?

31.  Why do objects float or sink when placed on the surface of water? Explain with an activity.
32. When would an object float in a liquid?
33. When would an object sink in a liquid?

ARCHIMEDES' PRINCIPLE

32. Define Archimedes' Principle.
33. Explain Archimedes' Principle with an example.
34. List the applications of Archimedes' Principle.

RELATIVE DENSITY

35. What is density?
36. What is the unit of density?
37. Define relative density.
38. Relative density = ---------------------.
39. Relative density has an unit. True or False?