The NCERT solutions is written in a simple language, which will not only help the students to grasp the basic concepts but also will help them to learn the topics by understanding.
CBSE NCERT Solutions for Class 8 Science Chapter 13:
A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
Frequency of oscillations is the number of oscillations of a vibrating object per
second. Therefore frequency is = 40 vibrations /4 seconds= 10 Hertz. Time period is the time required to complete one oscillation. Or it is the inverse of time
period. Therefore time period = 1/10 = 0.1 seconds.
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?
Time Period given by the inverse of the frequency.
Time Period= 1/Frequency of oscillation = 1/500 = 0.002 sec.
What is the difference between noise and music? Can music become noise
Unwanted sound that is unpleasant to ear is called noise. A pleasant sound is called
music. Music can become noise at many instances. When someone tries to enjoy very loud music, it can be noise for someone else. When loud music is played during religious celebrations or marriages, it can be annoying for many people.
Your parents are going to buy a house. They have been offered one on the
roadside and another three lanes away from the roadside. Which house would you
suggest your parents should buy? Explain.
There will be more noise in the house which is along the roadside due to noise
produced by transportation vehicles may cause trouble to the residents. On the other
hand, the house which is three lanes away from the roadside would be quieter. Therefore, it is better to take the house that is three lanes away from the roadside.