wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

A construction worker’s helmet slips and falls down when he is 78.4 m above the ground. He hears the sound of the helmet hitting the ground 4.23 seconds after it has slipped. Then find the speed of the sound in air.


A

512 m/s

No worries! We‘ve got your back. Try BYJU‘S free classes today!
B

215 m/s

No worries! We‘ve got your back. Try BYJU‘S free classes today!
C

341 m/s

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D

651 m/s

No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is C

341 m/s


Let t be the time taken by the helmet to reach the ground.
Here, u = 0, h = 78.4 m and g = 9.8 m/s2
h=12gt278.4=12×(9.8)×t2
or t2=2×78.49.8 or t=4 sec
The time taken by the helmet to drop to the ground = 4 s
The time taken by sound to travel 78.4 m = (4.23 - 4)s = 0.23 s
The speed of sound in air
=78.4 m0.23 s=340.87 m/s341 m/s


flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Speed of sound
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon