First slide
Elastic behaviour of solids
Question

A 0.1kg mass is suspended from a wire of negligible mass. The length of the wire is 1m  and its cross sectional area is 4.9×107 m2 . If the mass is pulled  slightly in the vertically downward direction and then released, it performs simple harmonic motion of angular frequency  140 rad/s. Then the Young’s modulus of material of the wire is(Assume that the Hooke’s law is valid throughout the motion )

Moderate
Solution

We know that  ω=km……….. (i)
Here  Y=FLAlF=YALl
Comparing the above equation with F=kl we get 
k=YAL…….. (ii)
From equations (i) and (ii) we get 
140=Y×4.9×1070.1×1
Y=4×109 N/m2 
Therefore, the correct answer is (A).
 

Get Instant Solutions
When in doubt download our app. Now available Google Play Store- Doubts App
Download Now
Doubts App