Physics · 2015
JEE Main · 11 April 2015, Shift 1 · Q13
A source of sound emits sound waves at frequency f_0. It is moving towards an observer with fixed speed v_s (v_s <v., where v is the speed of sound…
A source of sound emits sound waves at frequency $\displaystyle \mathrm{f}_0$. It is moving towards an observer with fixed speed $\displaystyle v_{\mathrm{s}}\left(v_{\mathrm{s}}<v\right.$, where $\displaystyle v$ is the speed of sound in air). If the observer were to move towards the source with speed $\displaystyle v_0$, one of the following two graphs (A and B) will give the correct variation of the frequency f heard by the observer as $\displaystyle v_0$ is changed.
The variation of f with $\displaystyle v_0$ is given correctly by :
The variation of f with $\displaystyle v_0$ is given correctly by :Official answer
(1)
graph A with slope $\displaystyle =\frac{f_0}{\left(v-v_{\mathrm{s}}\right)}$
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JEE Main 2015 Physics question, with the answer from NTA’s final answer key. Where our answers come from.