A speeding motorcyclist sees traffic jam ahead him. He slows down to $36\,\, km\,\,hour^{-1}$ He finds that traffic has eased and a car moving ahead of him at $18 \,\, km\,\,hour^{-1}$ is honking at a frequency of $1392\,\, Hz.$ If the speed of sound is $343\, m s^{-1}$, the frequency of the honk as heard by him will be .... $Hz$
AIPMT 2014, Medium
Download our app for free and get started
Here, speed of motorcyclist, $v_{m}=36 \mathrm{km}$ hour $^{-1}$
$=36 \times \frac{5}{18}=10 \mathrm{ms}^{-1}$
Speed of car,
$v_{c}=18 \mathrm{km} \text { hour }^{-1}=18 \times \frac{5}{18} \mathrm{ms}^{-1}=5 \mathrm{ms}^{-1}$
Frequency of source, $v_{0}=1392 \mathrm{Hz}$
Speed of sound, $v=343 \mathrm{ms}^{-1}$
The frequency of the honk heard by the motorcyclist is
$v^{\prime} =v_{0}\left(\frac{v+v_{m}}{v+v_{c}}\right)=1392\left(\frac{343+10}{343+5}\right)$
$=\frac{1392 \times 353}{348}=1412 \mathrm{Hz}$
Download our appand get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Similar Questions
- 1Spacing between two successive nodes in a standing wave on a string is $x$ . If frequency of the standing wave is kept unchanged but tension in the string is doubled, then new spacing between successive nodes will becomeView Solution
- 2A progressive wave travelling in positive $x$-direction given by $y=a \cos (k x-\omega t)$ meets a denser surface at $x=0, t=0$. The reflected wave is then given byView Solution
- 3Out of the given four waves $(1), (2), (3)$ and $(4)$View Solution
$y = a\sin (kx + \omega t)$ ......$(1)$
$y = a\sin (\omega t - kx)$ ......$(2)$
$y = a\cos (kx + \omega t)$ ......$(3)$
$y = a\cos (\omega t - kx)$ ......$(4)$
emitted by four different sources ${S_1},\,{S_2},\,{S_3}$ and ${S_4}$ respectively, interference phenomena would be observed in space under appropriate conditions when
- 4A closed and an open organ pipe have same lengths. If the ratio of frequencies of their seventh overtones is $\left(\frac{a-1}{a}\right)$ then the value of $a$ isView Solution
- 5If the phase difference between the two wave is 2$\pi $ during superposition, then the resultant amplitude isView Solution
- 6A travelling wave in a stretched string is described by the equation $y = A\sin (kx - \omega t)$. The maximum particle velocity isView Solution
- 7View SolutionApparatus used to find out the velocity of sound in gas is
- 8Two vibrating tuning forks produce progressive waves given by ${Y_1} = 4\sin 500\pi t$ and ${Y_2} = 2\sin 506\pi t.$ Number of beats produced per minute isView Solution
- 9One end of a taut string of length $3 \ m$ along the $x$-axis is fixed at $x=0$. The speed of the waves in the string is $100 \ m / s$. The other end of the string is vibrating in the $y$-direction so that stationary waves are set up in the string. The possible waveform$(s)$ of these stationary waves is (are)View Solution
$(A)$ $y(t)=A \sin \frac{\pi x}{6} \cos \frac{50 \pi t}{3}$
$(B)$ $y(t)=A \sin \frac{\pi x}{3} \cos \frac{100 \pi t}{3}$
$(C)$ $y(t)=A \sin \frac{5 \pi x}{6} \cos \frac{250 \pi t}{3}$
$(D)$ $y(t)=A \sin \frac{5 \pi x}{2} \cos 250 \pi t$
- 10If two waves having amplitudes $2A$ and $A$ and same frequency and velocity, propagate in the same direction in the same phase, the resulting amplitude will beView Solution