Two cars moving in opposite directions approach each other with speed of 22 m/s and 16.5 m/s respectively. The driver of the first car blows a horn having a frequency 400 Hz. The frequency heard by the driver of the second car is [velocity of sound 340 m/s]

Question

Question

Answer 1

Concept:

If two objects are moving towards each other then their relative speed is sum of speed of both objects.

Let v₁ and v2 be speed of the body 1(source) and 2(observer) moving towards each other.

Let f1 and f2 be frequency from source and frequency observed by observer.

Then, \(\rm f_2=f_1\left[\frac{v + v_2}{v - v_1}\right]\)

where v is velocity of sound in air.

Calculation:

Given:

Frequency of horn, f = 400 Hz

Speed of observer, v₀ = 16.5 m/s

Speed of source, v_s = 22 m/s

speed of sound, v = 340 m/s

Then

\(\rm f_A=f\left[\frac{v + v_o}{v - v_s}\right]\)

\(\rm =400\left[\frac{340 + 16.5}{340-22}\right]\)

f_A = 448 HZ

Download Solution PDF