Worksheet -3 (Nutrition in animals)

 Worksheet -3 




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Sound (part -1) class 8

SOUND Q.1. What is sound? Ans. Sound is a form of energy, a sensation felt by our ears and makes us able to hear something. We hear many sounds around us like: sounds of talking, chirping of birds, ringing of bell, fluttering of clothes, machines etc. Q.2. What is the cause of sound? Ans. Vibration in an object produces sound. To and fro or back and forth motion of an object is called vibration. The energy required to make an object vibrate and produce sound is provided by some outside sources (like our hands, wind etc.). For example: We can feel vibrations by keeping our hand on our throat while speaking where vocal cords vibrate to produce sound. The sound of a ‘Dholak or tabla’ is produced by the vibrations of its stretched membrane on strucking. Q.3. Tabulate the Musical Instruments and their Vibrating Parts which vibrate to produce sound. Ans. S.No. Vibrating Part of Instrument Producing Sound Examples 1. Stretc...
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Sound (part -3) class 8

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                                                                                                   SOUND Q.6.  Draw a well labeled diagram of human ear and explain its functioning? Ans. A human ear is divided into 3 parts: 1. Outer Ear : It is the only part of the ear that is visible to us. It consists of Pinna, Ear Canal and Ear Drum. The Pinna collects the sound waves and directs them to the ear canal. At the end of ear canal, there is ear drum which is slightly stretched membrane. When the vibrations strike the ear drum, it starts vibrating and transmits the sound to the middle ear. 2. Middle Ear : The middle ear is a cavity with three tiny important ear bones. These bones are M...
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Sound (part -4) class 8

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  SOUND Characteristics of sound Q.8. Define the following terms: Frequency, time-period and amplitude. Ans. Frequency : The number of oscillations per second is called the frequency of oscillation. Frequency is expressed in hertz. Its symbol is Hz. Time-period : The time period is  the time taken by the oscillating object to complete oscillation. It is expressed in seconds.   Amplitude : the amount of maximum displacement of vibrating particles of the medium from their mean position is called the Amplitude of oscillation. It is also known as size of vibration. The SI unit of amplitude is  the meter. Q.9. A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency. Q.10. The sound from a mosquito is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration? Q .11. How c an we differentiate sounds on the basis of their am...
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