Physics-
General
Easy
Question
Two trains A and B are moving with speeds 20 m/ s and 30 m/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 trains A blows a long whistle
Assume that the sound of the whistle is composed of components varying in frequency from f1 = 800 Hz to f2 = 1120 Hz, as shown in the figure. The spread in the frequency (highest frequency – lowest frequency) is thus 320 Hz. The speed of sound in still air is 340 m/s
The speed of sound of the whistle is
- 340 m/s for passengers in A and 310 m/s for passengers in B
- 360 m/s for passengers in A and 310 m/s for passengers in B
- 310 m/s for passengers in A and 360 m/s for passengers in B
- 340 m/s for passengers in both the trains
The correct answer is: 360 m/s for passengers in A and 310 m/s for passengers in B
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