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1. Reproduction in Organism
2. Sexual Reproduction in Flowering Plants
3. Human Reproduction
4. Reproductive Health
5. Principles of Inheritance and Variation
6. Molecular Basis of Inheritance
7. Evolution
8. Human Health and Disease
9. Strategies for Enhancement in Food Production
10. Microbes in Human Welfare
11. Biotechnology Principles and Processes
12. Biotechnology and its Applications
13. Organisms and Populations
14. Ecosystem
15. Biodiversity and Conservation
16. Environmental Issues

1.The Living World
2. Biological Classification
3. Plant Kingdom
4. Animal Kingdom
5. Morphology of Flowering Plants
6. Anatomy of Flowering Plants
7. Structural Organisation in Animals
8. Cell The Unit of Life
9. Bio molecules
10. Cell Cycle and Cell Division
11. Transport in Plants
12. Mineral Nutrition
13. Photosynthesis in Higher Plants
14. Respiration in Plants
15. Plant Growth and Development
16. Digestion and Absorption
17. Breathing and Exchange of Gases
18. Body Fluids and Circulation
19. Excretory Products and their Elimination
20. Locomotion and Movement
21. Neural Control and Coordination
22. Chemical Coordination and integration

Sound is produced due to the vibration of objects. Vibration is the rapid to and fro motion of an object.

Vibrating objects are the source of all sounds Irregular, chaotic vibrations produce noise Regular, controlled vibration can produce music All sound is a combination of pure frequencies
A stretched rubber band when plucked vibrates and produces sound.

2. Propagation of Sound

When an object vibrates, the particles around the medium vibrate. The particle in contact with the vibrating object is first displaced from its equilibrium position

The disturbance produced by the vibrating body travels through the medium but the particles do not move forward themselves.

A wave is a disturbance which moves through a medium by the vibration of the particles of the medium. So sound is considered as a wave.Sound waves Require medium for transmission.Sound waves are called mechanical waves. When a vibrating object moves forward, it pushes and compresses the air in front of it forming a region of high pressure called compression (C). When the vibrating object moves backward, it forms a region of low pressure called rarefaction (R).

A vibrating object producing a series of compressions (C) and rarefaction (R)
In these waves the particles move back and forth parallel to the direction of propagation of the disturbance. Such waves are called longitudinal waves.

There is another kind of waves called transverse waves. In these waves the particles oscillate up and down perpendicular to the propagation of the direction of disturbance.
Sound propagates in a medium as a series of compressions (C) and rarefactions (R).
Compressions are the regions of high pressure and density where the particles are crowded and are represented by the upper portion of the curve called crest.
Rarefactions are the regions of low pressure and density where the particles are spread out and are represented by the lower portion of the curve called trough

Characteristics of a sound wave

Frequency of sound wave

The number of oscillations per unit time is called the frequency of the sound wave.
It is represented by the symbol ٧ (Greek letter nu). Its SI unit is hertz (Hz)

Time period of sound wave
Frequency and time are represented as follows:-

٧ for one oscillation

Amplitude of sound wave

The amplitude of sound wave is the height of the crest or tough.
It is represented by the letter A. The SI unit is the same as that of density or pressure.Wavelength
 

The wavelength is the distance between the "crests" of two waves that are next to each other. The amplitude is how high the crests are

Pitch and loudness of sound

The pitch of sound (shrillness or flatness) depends on the frequency of vibration.

If the frequency is high, the sound has high pitch and if the frequency is low, the sound has low pitch
Speed of sound

The speed of sound is more in solids, less in liquids and least in gases.

The speed of sound also depends on the temperature of the medium. If the temperature of the medium is more, the speed of sound is more

3. Reflection of Sound

Sound gets reflected at the surface of a solid or liquid and follows the laws of reflection.

i) The angle of incidence is equal to the angle of reflection.

ii) The incident ray, the reflected ray and normal at the point of incidence all lie in the same plane

4. Echo

If we shout or clap near a reflecting surface like tall building or a mountain, we hear the same sound again. This sound which we hear is called echo. It is caused due to the reflection of sound.

To hear an echo clearly, the time interval between the original sound and the echo must be at least 0.1 s.

Since the speed of sound in air is 344 m/s, the distance travelled by sound in 0.I s = 344 m/s x 0.1 s = 34.4 m

So to hear an echo clearly, the minimum distance of the reflecting surface should be half this distance that is 17.2 m.

Reverberation

Echoes may be heard more than once due to repeated or multiple reflections of sound from several reflecting surfaces. This causes persistence of sound called reverberation. In big halls or auditoriums to reduce reverberation, the roofs and walls are covered by sound absorbing materials like compressed fibre boards, rough plaster or draperies.

5. Uses Of Multiple Reflection Of Sound

Megaphones, horns, musical instruments like trumpets, etc. are deigned to send sound by multiple reflection in a particular direction without spreading in all directions.

ii) Doctors listen to sounds from the human body through a stethoscope. The sound of heartbeat reaches the doctor’s ears by multiple reflection.

iii) Generally the ceilings of cinema halls and auditoriums are curved so that sound after multiple reflection reaches all parts of the hall. Sometimes a curved sound board is placed behind the stage so that sound after multiple reflection spreads evenly across the hall.

6. Range of Hearing

Human beings can hear sound frequencies between 20 Hz and 2000 Hz

Sound whose frequency is less than 20 Hz is called infrasonic sound
Sound whose frequency is more than 2000 Hz is called ultrasonic sound

7. Uses of ultrasonic sound

Ultrasonic sound is used to clean objects like electronic Components, used to detect cracks in metal blocks, used in ultra sound scanners for getting images of internal organs of the human body used to break small stones formed in the kidneys into fine grains.

8 Sonar

It is a device which uses ultrasonic waves to measure distance, direction and speed of underwater objects. The distance of the object can be calculated by knowing the speed of sound in water and the time taken between the transmission and reception of ultrasound

9.Structure  of the human ear

The sound waves passes through the ear canal to a thin membrane called eardrum. The eardrum vibrates. The vibrations are amplified by the three bones of the middle ear called 130 hammer, anvil and stirrup. Middle ear then transmits the sound waves to the inner ear. The brain then interprets the signals as sound.

QUESTION BANK

One mark questions

1. What do you understand by sound waves?

2. Give an example to show that sound travels at a finite speed.

3. Is sound wave longitudinal or transfer.

4. Name two quantities that vary periodically at a place in air as a sound wave travels through it .

5. An airplane produces a sound wave with frequency of 5 KHz and wavelength 30 m. In how much time would the sound wave cover the distance of 4 Km?

6. With the help of a diagram show how longitudinal waves like sound waves travel in air.

7. With the help of a diagram show how longitudinal waves like sound waves travel in air.

8. Can we hear the ringing of a mobile phone placed in a vacuum chamber?

9. Can two astronauts talk on moon a they does on the surface of the earth?

Two marks questions

1. Explain how echoes are used by bats to judge the distance of an obstacle?

2. State the special properties of ultrasound that make it useful to us .In general, how these properties are utilized.

3. Why is soft furnishing avoided in concert halls?

4. Draw a diagram depicting low pitched sound and high pitched sound and write main difference between the two?

5. Distinguish between longitudinal and transverse waves.

6. An explosion takes place at the moon. After what time would it be heard at the earth?

Give one example each.

Three marks questions

1. Two sources A and B vibrate with the same amplitude. They produce sounds of frequencies 1 kHz and 30 kHz respectively. Which of the two waves will have greater power?

2. Find the time period of the source of a sound wave whose frequency is 400Hz.

3. A sound wave travels at a speed of 340m/s. If its wavelength is 2 cm, what is the frequency of the wave? Will it be in the audible range?

4. The grandparents and parents of a two year girl are playing with her in a room. A sound source produces a 28—kHzsound.who in the room is most likely to hear the sound?

Five marks questions

1. Sound cannot travel in vacuum. Describe an experiment to demonstrate this.

2. With the help of a diagram describe how compression and rarefaction pulses are produced in air near a source of sound. 3. Explain briefly how a flaw in a mental component can be detected using ultrasound?

4. Explain the working and application of SONAR.

5. A monkey drops a coconut from the top of a tree. He hears the sound of the coconut hitting the ground 2.057 seconds after dropping it .If the monkey was 19.6 metres above the ground, what is the speed of sound in air?(take g = 9.8m/s2.

6. Draw a neat diagram of human ear. Explain the function of various parts.

What have you learnt Longitudinal waves:

Those in which the direction of vibration is the same as their direction of propagation. So the movement of the particles of the medium is either in the same or in the opposite direction to the motion of the wave. Exemple: sound waves, what changes in this case is the pressure of the medium (air, water or whatever it be). Transverse waves: The oscillations occur perpendicularly to the direction of energy transfer.

Exemple: a wave in a tense string. Here the varying magnitude is the distance from the equilibrium horizontal position A general property of waves is that their speed relative to medium depends on the properties of medium but is independent of the motion of the source of waves. If the observer is in motion with respect to the medium, the velocity of wave propagation relative to the observer wil be different. A remarkable exception is encountered in the case of light

PROPERTIES

Frequency -
Wavelength -
Period -
Amplitude -
Intensity -
Speed -
Direction Perception of Sound For humans, hearing is limited to frequencies between about 20 Hz and 20000 Hz, with the upper limit generally decreasing with age.

KEY LEARNING :

Vibration -
repetitive back and forth motion Periodic motion -
a motion that repeats itself Mechanical waves require medium for propagation Waves move through medium but medium remains in place Longitudinal waves-Vibration direction parallel to wave propagation direction Particles in medium move closer together/farther apart .Example: sound waves Gases and liquids -
support only longitudinal waves Transverse waves-
Vibration direction perpendicular to wave propagation direction .Example: plucked string Solids -
support both longitudinal and transverse waves Sound waves Require medium for transmission 1. Sound is a wave motion, produced by a vibrating source.

2. A medium is necessary for the propagation of sound waves.

3. Sound is a longitudinal wave in which the particles of medium move along the direction of motion of wave.

4. The part or region of a longitudinal wave in which the density of the particles of the medium is higher than the normal density is known as compression.

5. The part or region of a longitudinal wave in which the density of the particles of the medium is lesser than the normal density is called a rarefaction.

6. The point of maximum positive displacement on a transverse wave is known as crest.

7. The point of maximum negative displacement on a transverse wave is known as through.

8. A wave or short duration which is confined to a small portion of a medium at any given time is known as a pulse.

9. The maximum displacement of particles of the medium from their mean positions during the propagation of a wave is known as amplitude of the wave.

10. The distance traveled by a wave in one second is called wave velocity. It depends upon the nature of the medium through which it passes.

11. The speed of sound depends primarily on the nature and the temperature of the transmitting medium.

12. Sound travels faster in solids than in air. The speed of sound in solids is much more than the speed of sound in liquids or gases.

13. The distance between two consecutive compressions or two consecutive rarefactions is called the wavelength.

14. Frequency is defined as the number of oscillations per second.

15. The time taken by the wave for one complete oscillation of the density or pressure of the medium is called the time period, T.

16. How the brain interprets the frequency of an emitted sound is called the pitch of sound.

17. Loudness is the degree of sensation of sound produced .

18. Sound properties such as pitch, loudness and quality are determined by the corresponding wave properties.

19. Sound gets reflected and follows the same law as the reflection of light.

20. The persistence of sound due to repeated reflection and its gradual fading away is called reverberation of sound.

21. Echo is a repetition of sound due to the reflection of original sound by a large and hard obstacle.

22. The audible range of hearing for average human beings is in the frequency range of 20 Hz – 20 kHz.

23. The amount of sound energy passing each second through unit area is called the intensity of sound.

24. Sound of frequency less than 20 Hz is known as infrasound and greater than 20 kHz is known as ultrasound.

25. Ultrasound has many medical and industrial applications.

26. SONAR stands for Sound Navigation and Ranging and it works on the principle of reflection of sound waves.

27. The SONAR technique is used to determine the depth of the sea and to locate under water hills, valleys, submarines, icebergs sunken ships etc.

1.Work Done By A Constant Force

• Work is a scalar quantity equal to the product of the displacement x and the component of the force F_x in the direction of the displacement..

• Work is defined as a force acting upon an object to cause a displacement

• Mathematically, work can be expressed by the following equation.

• W= F x d cos q ( cos 0^o = 1)

• where F = force, d = displacement, and the angle (theta) is defined as the angle between the force and the displacement vector

• Three things are necessary for the performance of work

• There must be an applied force F.

• There must be a displacement x.

• The force must have a component along the displacement

Test Yourself:

1.Calculate Work when F= 40 N and x = 4 m.

2.Calculate Work when F = -10 N and x = 4 m.

3. A lawn mower is pushed a horizontal distance of 20 m by a force of 200 N directed at an angle of 30^o with the ground. What is the work of this force?

4. A student lifts a 50 pound (lb) ball 4 feet (ft) in 5 seconds (s). How many joules of work has the student completed?

2.Energy And Its Forms

James Joule

The metric system unit of energy is the joule (J), after James Joule.

• Mechanical energy is the energy which is possessed by an object due to its motion or its stored energy of position

Forms of Energy

• Kinetic energy : is the energy of motion
Energy which a body possesses because of its motion, which occurs anywhere from an atomic level to that of a whole organism

Examples of Kinetic Energy: This is not an all-inclusive list.

• Electrical – The movement of atoms

• Electromagnetic or Radiant – The movement of waves

• Thermal or Heat – The movement of molecules

• Motion – The movement of objects

• Sound – The movement through waves
Engineers generally refer to thermal/heat energy as “internal energy” and use “kinetic energy” strictly in reference to motion.
Potential Energy (Stored energy or gravitational energy)

• The capacity to do work by virtue of position or configuration

• an object can store energy as the result of its position or elastic source

• Potential Energy is maximum at the maximum HEIGHT

Energy transformation involves the conversion of one form of energy into another form.
Examples of energy transformation include:

• Chemical – Food is consumed and converted into motion for playing sports or taking a test.

• Radiant – Sunlight is consumed by plants and converted into energy for growth

• Electrical – Energy transferred to an oven is converted to thermal energy for heating our food.

Now you know the basic forms of energy. The next question is “What are the energy sources?”
There are renewable and nonrenewable sources of energy. A renewable energy source is a form of energy that is constantly and rapidly replenished by natural processes.
Examples of renewable energy sources include:

• Biomass – The use of a living or once living organism as fuel

• Hydropower – The energy produced from the movement of water

• Geothermal – The use of heat from within the Earth or from the atmosphere near oceans to warm houses or other buildings

• Wind – The use of wind to generate electricity

Solar – The use of the sun as a source of heat; for instance, to heat a room within a house, etc.

Energy Conversion

Examples

Fossil fuels Chemical → Heat → Mechanical → Electrical

Solar cells Sunlight → Electrical

Wind turbines Kinetic → Mechanical → Electrical

Hydroelectric Gravitational potential → Mechanical → Electrical

Nuclear       Nuclear → Heat → Mechanical → Electrical

Test Yourself

1. How much potential energy is lost by a 5Kg object to kinetic energy due a decrease in height of 4.5 m.

3. Potential energy of an object at a height
An object increases its energy when raised through a height.
The potential energy of an object at a height depends on the ground level or the zero level

4. Law Of Conservation Of Energy

The principle of Conservation of Mechanical Energy
The total mechanical energy (E=KE+PE) of an object remains constant as the object moves, provided that the net work done by external non-conservative forces is zero, W_nc=0J
Total mechanical energy: the sum of kinetic energy and gravitational potential energy

E = KE + PE
W_nc = (KE_f - KE_o) + (PE_f - PE_o)
W_nc = (KE_f + PE_f) - (KE_o + PE_o)
W_nc = E_f - E_o
E_f = KE_f + PE_f) E_o = KE_o + PE_o

5. Rate of Doing Work & Commercial Unit Of Energy POWER
Rate at which work is performed or energy is expended

Watt is the base unit of Power

One watt is equal to 1 joule of work per second
Types of Power

• Electrical Power
Uses electrical energy to do work

• Mechanical Power
Uses mechanical energy to do work (linear, rotary)

• Fluid Power
Uses energy transferred by liquids (hydraulic) and gases (pneumatic)

• Power is the rate that we use energy.

• Power = Work or Energy / Time

• P = W/t = F x d/t = F v

• The unit joule is too small .The bigger unit of energy called kilowatt hour (kW h)
1 kW h is the energy used in one hour
at the rate of 1000 J s–1 (or 1 kW).

1 kW h = 1 kW *1 h

= 1000 W*3600 s

= 3600000 J

1 kW h = 3.6 x 10⁶ J. WP=t

Test Yourself

1. A 5 Kg Cart is pushed by a 30 N force against friction for a distance of 10m in 5 seconds. Determine the Power needed to move the cart.

2. A student lifts a 50.0 pound (lb) ball 4.00 feet (ft) in 5 .00seconds (s). How many watts of power are used to lift the ball?
Important Points for Work Problems:

• Always draw a free-body diagram, choosing the positive x-axis in the same direction as the displacement.

• Work is negative if a component of the force is opposite displacement direction

• Work done by any force that is at right angles with displacement will be zero (0).

• For resultant work, you can add the works of each force, or multiply the resultant force times the net displacement.

• Energy is the ability to move

• Potential is stored energy (Statics)

• Dependant on height

• Kinetic is moving energy (Dynamics)

• Dependant on velocity

• Springs store energy dependant on distance and constant

QUESTION BANK

One mark questions

1. Does work have a direction?

2. Does the kinetic energy of an object depend on its direction of motion?

3. Cam matter be converted into energy?

4. Give an example of conversion of chemical energy into heat energy.

Two marks questions

1. Two persons do the same amount of work. The first person does it in 10 s and the second, in 20 s.Find the ratio of the power used by the person to that by the second person.

2. A body of mass 25 g has a momentum of 0.40 kgm/s.Find its kinetic energy.

3. Define work and write its units.

4. By what factor does the kinetic energy of an object depend on its direction of motion?

Three marks questions

1. How much time will it take to perform 440 j of work at a rate of 11 W.

2. A body of mass 3.0kg and a body B of mass 10 kg are dropped simultaneously from a height of 14.9m.Calculate their Momenta, their Potential energies and kinetic energies when they are 10m above the ground.

3. lA man does 200j ofl work in 10 seconds and a boy does 100j of work in 4 seconds. Who is delivering more power? Find the Ratio of power delivered by the man to that by the boy.

Five marks questions

1. Show that the work done by a force is given by the product of the force and the projection of the displacement along the force.

2. Find the expression for gravitational potential energy of a body of mass m at height h.

3. Why does a person standing for a long time get tired when he does not appear to do any work?

4. How can you justify that a body kept at a greater height has larger energy?

• Distance: How far an object has moved. It has only magnitude without direction. (total)

•Displacement: How far and in what direction an object has moved from its start position. i.e. the direct distance between two points. Speed                

• Distance: How far an object has moved. It has only magnitude without direction. (total)

• Displacement: How far and in what direction an object has moved from its start position. i.e. the direct distance between two points.

Speed

• Speed = the distance an object travels in a given amount of time

• UI unit of speed is m/s

Types of Speed

• Constant speed: speed doesn’t change (set your car on cruise control)

• Changing speed: Riding a bike for 5 km. Take off and increase speed, slow down up hill, speed up down hill, stop for stop sign. The trip took you 15 min (.25 h)

• Instantaneous speed: speed at any given time.

Velocity

• Velocity: includes speed and DIRECTION
• Storm is moving at 20km/hr.
• Should you be seeking shelter?
• Suppose two trains are going with the same speed in opposite direction so they are having different velocities.
• Race car going around an oval track might have constant speed, but different velocities at each point.

Acceleration

• Any change in velocity over a period of time is called acceleration.
• The sign (+ or -) of indicates its direction. + sign shows the acceleration and – sign shows de-acceleration.
• Uniform (constant) acceleration equation
• a = v/t

• Images of car are equally spaced.
• The car is moving with constant positive velocity (shown by red arrows maintaining the same size) .
• The acceleration equals to zero

• Images of car become farther apart as time increase

• Velocity and acceleration are in the same direction

• Acceleration is uniform (Arrows below the car maintain the same length)

• Velocity is increasing (Arrows above the car are getting longer)

• This shows positive acceleration and positive velocity

The instant speed at points of equal elevations is the same.
The velocities are different because they are in opposite
Free Fall & Air Resistance

Galileo Galilei Italian physicist and astronomer Formulated laws of motion for objects in free fall

• A freely falling object is any object moving freely under the influence of gravity alone.

• It does not depend upon the initial motion of the object

• Dropped – released from rest

• Thrown downward

• Thrown upward

• The acceleration of an object in free fall is directed downward, regardless of the initial motion

• The magnitude of free fall acceleration (gravitational acceleration) is g = 9.80 m/s²

• g decreases with increasing altitude

• g varies with latitude, height and depth from earth surface.

• 9.80 m/s2 is the average at the Earth’s surface

• The italicized g will be used for the acceleration due to gravity

• Not to be confused with g for grams

• With negligible air resistance, falling objects can be considered freely falling.
objects of different shapes accelerate differently (stone vs feather)
• Speed both upward and downward

• The path is symmetrical.

• Acceleration is constant.

• The magnitude of the velocities is the same at equal heights.

• Images become closer together as time increases

• Acceleration and velocity are in opposite directions when ball goes upward.

• Acceleration is uniform (violet arrows maintain the same length)

• Velocity is decreasing in upward motion (red arrows are getting shorter)

• Positive velocity and negative acceleration

• Velocity becomes zero at maximum height.

• Time duration flight in going upward and coming back is always same.

Test Yourself :

1. What is SI Unit of displacement?

2. Name the quantity which represents rate of change of velocity.

3. A particle describes a semicircle of radius l 14m. What are its distance and displacement covered?

2 Graphical Representation Of Motion & Graphs (Refer to article 8.4 of NCERT text book.)

Test Yourself :

1. What does slope of Position – Time graph represent?

2. If velocity –time graph is parallel to time axis, what type of motion does it represent?

3 Equation of motion

(1) When object is moving in straight line-

• v = v_o + at

• x = x_o + vot + ½ at²

• v² = v_o² + 2a(Δx)

• Average acceleration describes how fast the velocity is changing with respect to time.

• where: aave = average acceleration

Δv = change in velocity

Δx = displacement

Δt = elapsed time

(2) when object is coming vertically downward-

•v = v_o + gt

• h = v_ot + ½ gt²s

• v² = v_o² + 2ah

(3) when object is coming vertically upward-

v = v_o - gt

h = v_ot - ½ gt²

v² = v_o² - 2gh

• The SI unit of velocity is the m/s.
Average accleration is + or – depending on direction.

• Instantaneous Acceleration

• Instantaneous acceleration is the limit of Δv/Δt as Δt approaches zero.

• Instantaneous acceleration is zero where slope is constant

• Instantaneous acceleration is positive where curve is concave up

• Instantaneous acceleration is negative where curve is concave down

Test Yourself :

1. Give the equation for uniform motion.

2. When a car stops after applying brakes, what is the final velocity?

4 Uniform Circular Motion

In this kind of motion the object moves on circle with fix speed but the direction is changed by the time so the velocity of the change so its called acceleration motion. This acceleration is called centrifugal acceleration. It is directed toward the centre.

Test Yourself:

1. What remains constant in uniform circular motion?

2. What changes continuously in uniform circular motion?

QUESTION BANK

One Mark questions

1. Can displacement be zero even when distance is not zero?

2. Can the distance travelled by an object be smaller than magnitude of its displacement?

3. A particle is moving with uniform velocity. What is its acceleration?

4. How can you get speed of an object from its distance – time graph?

5. How can you get distance of an object from its speed – time graph?

6. A brick & an elephant are in free fall. What is common in their motion?

7. When an object is thrown vertically upwards. What is its velocity at the highest point?

8. Can velocity & acceleration point in opposite directions?

9. Define acceleration.

10. What is non uniform motion?

Two Marks questions

1. Differentiate scalars & vectors?

2. What is retardation? How does it affect the speed?

3. Can speed of a body vary with its velocity constant? Explain.

4. Why is circular motion with constant speed called accelerated motion?

5. State the difference between distance & displacement.

6. What is the difference between speed & velocity?

7. What does a speedometer & odometer indicate?

Three Marks questions

1. If an object is thrown vertically upwards with speed 49 ms-1. How long does it take to complete upward journey? What maximum height does it achieve?

2. An object starting from rest covers 20 metres in first 2 seconds & 160 metres in next 4 seconds. What is its velocity after 7 seconds from the start?

Five Marks questions

1. Derive all the three equations of motion for uniform acceleration using graphical method.

2. A car a moving at rate of 72km/h and applies brakes which provide a retardation of 5ms-2.

(i) How much time does the car takes to stop.

(ii) How much distance does the car cover before coming to rest?

(iii) What would be the stopping distance needed if speed of the car is doubled?