Paragraph: Two trains A and B are moving with speeds 20 m / s and...

Paragraph: Two trains

A

and

B

are moving with speeds

20 \mathrm{ m} / \mathrm{s}

and

30 \mathrm{ m} / \mathrm{s}

, respectively in the same direction on the same straight track, with

B

ahead of

A

. The engines are at the front ends. The engine of train

A

blows a long whistle. Assume that the sound of the whistle is composed of components varying in frequency from

f_1=800 \mathrm{ Hz}

f_2=1120 \mathrm{ Hz}

, as shown in the figure. The spread in the frequency (highest frequency - lowest frequency) is thus

320 \mathrm{ Hz}

. The speed of sound in still air is

340 \mathrm{ m} / \mathrm{s}

.Question: The distribution of the sound intensity of the whistle as observed by the passengers in train

A

is best represented by Paragraph: Two trains A and B are moving with speeds 20 m / s and 30 m / s , respectively in the same direction on the

Options

Correct answer

A. cases Ag _ 2 S + NaCN & → & (A) (A) + Zn & → & (B) cases (B) is a metal. Hence, (A) and (B) are

Step-by-step solution

For the passengers in train

A

, there is no relative motion between source and observe, as both are moving with velocity

20 \mathrm{ m} / \mathrm{s}

. Therefore, there is no change in observed frequencies and correspondingly there is no change in their intensities. Therefore, the correct option is (a).

Practice Waves and Sound on Quantrex Academy →

More from Waves and Sound