1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

# A whistle emitting a loud sound of frequency 540Hz is whirled in a horizontal circle of radius 2m and at a constant angular speed of 15rad/s. The speed of sound is 330m/s. The ratio of the highest to the lowest frequency heard by a listener standing at rest at a large distance from the center of the circle is?

A
1.0
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
1.1
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
1.2
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
1.4
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

## The correct option is C 1.2Original frequency of the source fo=540 HzVelocity of sound in air vsound=330m/sAngular velocity of the source w=15rad/sRadius of circular orbit r=2mThus linear velocity of the source vsource=rw∴ vsource=2×15=30 m/sUsing Doppler effect when a source moves towards the stationary observer.Highest frequency heard by the observer f1=fo[vsoundvsound−vsource]∴ f1=540[330330−30]=540[330300]Using Doppler effect when a source moves away from the stationary observer.Lowest frequency heard by the observer f2=fo[vsoundvsound+vsource]∴ f2=540[330330+30]=540[330360]Thus ratio of frequencies f1f2=(540×330)/300(549×330)/360⟹ f1f2=360300=1.2

Suggest Corrections
0
Join BYJU'S Learning Program
Related Videos
What Sound Really Is
PHYSICS
Watch in App
Join BYJU'S Learning Program