NCERT Solutions for Chapter: Sound, Exercise 1: Exercise

State some sources of noise pollution.

Which of the following will not produce a musical sound?

Three persons $P_1$, $P_2$, and  $P_3$ are at different points A, B, and C, respectively, as shown in the figure. Two persons $P_1$ and  $P_3$ clap at the same time. Which among the following can be the minimum distance between $P_2$ and $P_3$ to hear the clap sound distinctly? (Take the velocity of sound in air as $330 \mathrm{m} {\mathrm{s}}^{-1}$)

The time period of a simple pendulum is given by the formula, $T=2\mathrm{\pi }\sqrt{\frac{\mathrm{l}}{\mathrm{g}}}$, where $T=$ time period, $l=$ length of pendulum and $g=$acceleration due to gravity.

If the length of the pendulum is decreased to $\frac{1}{4}$ of its initial value, then what happens to its frequency of oscillations?

A child pushed his cradle for play and started learning numbers by counting the oscillations of his cradle. He counted one number per one oscillation starting from $1$, then find the number of numbers the child learned and cradle frequency of oscillations for the total time of $60$ second, if the time period of the cradle is $2.5 \mathrm{s}$.

On a hot summer day, a little mosquito produces a warning sound near your ear by vibrating its wings at the rate of $3,000$wing beats per five seconds. State the frequency, in hertz, of this sound.

Standing between two hills, a researcher makes a loud sound. She hears two echoes at the end of $3 \mathrm{s}$ and $4 \mathrm{s}$. Using the survey map, she notes that the distance between the hills is $1190 \mathrm{m}$. What will be the speed of sound at that place?

The audible range of frequency is $20 \mathrm{Hz}$ to $20,000 \mathrm{Hz}$. Determine the corresponding range of time periods of vibrations.