Physics · 2019
JEE Main · 10 January 2019, Shift 1 · Q13
A train moves towards a stationary observer with speed 34 m / s. The train sounds a whistle and its frequency registered by the observer is f_1. If…
A train moves towards a stationary observer with speed $\displaystyle 34 \mathrm{~m} / \mathrm{s}$. The train sounds a whistle and its frequency registered by the observer is $\displaystyle f_1$. If the speed of the train is reduced to $\displaystyle 17$ m/s, the frequency registered is $\displaystyle f_2$. If speed of sound is $\displaystyle 340 \mathrm{~m} / \mathrm{s}$, then the ratio $\displaystyle f_1 / f_2$ is :
Official answer
(4)
$\displaystyle 19$/$\displaystyle 18$
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JEE Main 2019 Physics question, with the answer from NTA’s final answer key. Where our answers come from.