A train moves at 72 km/h toward a stationary observer and sounds a whistle of frequency 600 Hz — JEE Physics
A train moves at 72 km/h toward a stationary observer and sounds a whistle of frequency 600 Hz. Find the apparent frequency heard. (Speed of sound = 340 m/s)
1 Answer
VAVidaara Admin
✓ Vidaara Team
✓ Accepted
· 18d ago
▲ 3
$v_s = 72 \times \frac{5}{18} = 20$ m/s
$$f' = f \cdot \frac{v}{v - v_s} = 600 \times \frac{340}{340-20} = 600 \times \frac{340}{320}$$
$$f' = 600 \times 1.0625 = 637.5 Hz$$
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Discussion (5)
R
Is there a faster shortcut for this in the actual exam? Time is tight.
KS
I solved it a slightly different way and got the same answer, good sign.
VC
Saved me before my mock test. Much clearer than my coaching notes.
K
What changes if the medium/conditions were different?
VA
Good follow-up questions — remember to always state your assumptions in the JEE subjective section.