Worksheet -3 (Nutrition in animals)

 Worksheet -3 




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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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FORCE AND PRESSURE class 8

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FORCE Q.1. Define the term force. What are its characteristics? Ans. In science, a push or a pull on an object is called a force. The fo rce always has a measure of its strength or magnitude and direction in which it is applied. So, Force is a vector quantity. The S.I. unit of Force is N (Newton). Q.2. Forces are due to an Interaction. Justify.  Ans. At least two objects must interact for a force to come into play. This means whenever a force is applied on an object, three things can be easily observed: Ø agent exerting the force Ø the object on which it acts Ø the effect of the force                                                         Q.3.  W...
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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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