A train approaching a railway crossing at a speed of 120 km/hr sounds a short whistle at frequency $f_{o} = 640 H z .$ When it is 300 m away from the crossing. The speed of sound in air is 340 m/sec. A person standing on a road perpendicular to the track at a distance 400 m from the crossing , hears frequency $f_{1} .$ The value of $f_{1} - f_{0} = 10 x .$ Find the value of x

see full answer

High-Paying Jobs That Even AI Can’t Replace — Through JEE/NEET

🎯 Hear from the experts why preparing for JEE/NEET today sets you up for future-proof, high-income careers tomorrow.

An Intiative by Sri Chaitanya

answer is 4.

(Unlock A.I Detailed Solution for FREE)

JEE

NEET

Foundation JEE

Foundation NEET

CBSE

Detailed Solution

The component of the velocity of train along the line joining to the person is $v_{s} cosθ$

here, $v_{s} = \frac{100}{3} {ms}^{- 1}$ , $cosθ = \frac{3}{5}$

$f_{ap} = f_{0} [\frac{v + v_{o}}{v - v_{s} cosθ}] = 640 (\frac{340}{340 - \frac{3}{5} \times \frac{100}{3}}) = 680 Hz$

So, $f_{1} - f_{0} = 40 Hz$

Watch 3-min video & get full concept clarity

No courses found

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test