Long Answer Questions - Sound

Class 8 Science Chapter 11 Question Answers - Sound

Q1: Explain the mechanism of hearing in human body.

Ans: Sound plays an important role in our life; Sound helps us to communicate with one another.Sound is so important because animals are able to hear events all around them, no matter where their attention is focused or not. The eardrum, or tympanic membrane, is a thin, cone-shaped membrane that separates the external ear from the middle ear in humans, it is like a stretched rubber sheet, sound vibrations make the eardrum vibrate. The ear drum sends vibration to the inner ear and from there signal is send to the brain and in this way we are able to hear the sounds around us.
Q2: “Sound travels through a medium, it cannot travel in vacuum”. Justify the statement.

Ans: Sound travels through a medium solid, liquid and gas. It cannot travel through vacuum.Fill a bucket with water and shake a bell under the water with one hand make sure that the bell should not touch the body of the bucket. Now place your ear gently on the water surface, you will hear the sound of the ringing bell, thus we can say that sound can travel through water.Take a metal rod and hold its one end to your ear, ask your friend to tap at the other end of metal rod you will hear the sound of tapping, thus this proves that sound can travels through solid.
Q3: A pendulum oscillates 50 times in 6 seconds. Find its time period and frequency.

Ans: Frequency of oscillation is defined as the number of oscillation of a vibrating body per second. it is given by

Frequency = no of oscillation/ time period = 50/6 = 8.33 Hz

Time period =1/frequency of oscillation = 1/ 8.33 = 0.12 seconds.
Q4: The sound from a butterfly is produced when it vibrates its wings at an average rate of 400 vibrations per second. What is the time period of vibration?

Ans: Time period =1/frequency of oscillation = 1/ 400 0.0025 seconds

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FAQs on Class 8 Science Chapter 11 Question Answers - Sound

 1. What is sound and how is it produced?
Ans. Sound is a form of energy that is produced by vibrating objects. It is created when an object vibrates, causing the particles around it to vibrate as well. These vibrations then travel through a medium, such as air, and reach our ears, allowing us to hear the sound.
 2. What are the different types of sounds?
Ans. There are two main types of sounds: audible sounds and inaudible sounds. Audible sounds are the sounds that can be heard by the human ear, while inaudible sounds are the sounds that cannot be heard by the human ear, such as ultrasonic or infrasonic sounds.
 3. How does sound travel through different mediums?
Ans. Sound travels through different mediums by causing the particles in the medium to vibrate. In solids, sound travels through the particles that are closely packed together, allowing the vibrations to easily pass from one particle to another. In liquids, sound travels by causing the particles to vibrate and pass on the vibrations to neighboring particles. In gases, sound travels by causing the particles to compress and rarefy, creating areas of high and low pressure that propagate as sound waves.
 4. How does the pitch of a sound depend on its frequency?
Ans. The pitch of a sound is determined by its frequency. Higher frequencies correspond to higher pitches, while lower frequencies correspond to lower pitches. For example, a sound with a high frequency, such as a whistle, will have a high pitch, while a sound with a low frequency, such as a bass guitar, will have a low pitch.
 5. How does the loudness of a sound depend on its amplitude?
Ans. The loudness of a sound is determined by its amplitude. Amplitude refers to the maximum displacement of the particles in a sound wave. A sound with a larger amplitude will have a higher loudness, while a sound with a smaller amplitude will have a lower loudness. In other words, the greater the amplitude of a sound wave, the louder it will be perceived.

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