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

A uniform circular disc of mass 1 kg and radius 0.5 m is rotating about its axis with a constant angular velocity 5 rad/sec. Two birds, each of mass 0.25 kg sit gently at the opposite ends of the diameter of the disc. The final angular velocity of the disc will be

A
5 rad/sec
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
7.5 rad/sec
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
2.5 rad/sec
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
1 rad/sec
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is C 2.5 rad/sec
Let the final angular velocity of disc is ω2
Given, mass of disc, M=1 kg
radius of disc, r=0.5 m
Initial angular velocity of disc, ω1=5 rad/sec.
Mass of bird, m=0.25 kg

Since, net external torque on the system is zero. Therefore, angular momentum will remain conserved.
Thus,
Li=Lf
I1ω1=I2ω2
(12Mr2)ω1=(12Mr2+2mr2)ω2
(12×1×0.52)×5=(12×1×0.52+2×0.25×0.52)×w2
ω2=2.5 rad/sec
So, the final angular velocity of the disc will be 2.5 rad/sec.

flag
Suggest Corrections
thumbs-up
1
Join BYJU'S Learning Program
Join BYJU'S Learning Program
CrossIcon