A disc of mass 2kg and radius 0.2m is rotating with angular velocity 39rads−1. What is angular velocity, if two masses each of 0.25kg is put on periphery of the disc?
A
24rads−1
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
36rads−1
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
15rads−1
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
26rads−1
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution
The correct option is A24rads−1
Angular momentum in absence of any external torque remains constant. If no external torque acts on a system of particles, then angular momentum of the system remains constant,
i.e,τ=0⟹dLdt=0⟹L=Iω=constant
Initial angular momentum = Final angular momentum
⟹I1ω1=I2ω2
∴12Mr2ω1=12(M+2m)r2ω2...(i)
Here, M=2kg,m=0.25kg,r=0.2m,ω1=30rad/s
Hence, we get after putting the given values in Eq.(i)