can someone plz give me the numerical questions of physics of sound class 8th plz
Answers
Answer:
1) If a pendulum oscillates 20 times in 4 seconds. What is its time period?
2) Lightning can be seen the moment it occurs. Paheli observes lightning in her area. She hears the sound 5 s after she observed lightning. How far is she from the place where lightning occurs? (speed of sound = 330 m/s).
3) A simple pendulum makes 10 oscillations in 20 seconds. What is the time period and frequency of its oscillation?
4) Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440 m/s in a given medium.
5) A person is listening to a tone of 500 Hz sitting at a distance of 450 m from the source of the sound. What is the time interval between successive compressions from the source?
6) An echo returned in 3 s. What is the distance of the reflecting surface from the source, given that the speed of sound is 342 m s−1?
7) A submarine emits a sonar pulse, which returns from an underwater cliff in 1.02 s. If the speed of sound in salt water is 1531 m/s, how far away is the cliff?
8) A person has a hearing range from 20 Hz to 20 kHz. What are the typical wavelengths of sound waves in air corresponding to these two frequencies? Take the speed of sound in air as 344 m s−1.
9) Two children are at opposite ends of an aluminium rod. One strikes the end of the rod with a stone. Find the ratio of times taken by the sound wave in air and in aluminium to reach the second child.
10) The frequency of a source of sound is 100 Hz. How many times does it vibrate in a minute?
Explanation:
Hope this may help you.....