Rotational Motion Question 54
Question: A round disc of moment of inertia about its axis perpendicular to its plane and passing through its centre is placed over another disc of moment of inertia rotating with an angular velocity about the same axis. The final angular velocity of the combination of discs is:
[AIPMT (S) 2004]
Options:
A)
B)
C)
D)
Show Answer
Answer:
Correct Answer: A
Solution:
- Key Idea: When no external torque acts on a system of particles, then the total angular momentum of the system remains always a constant.
The angular momentum of a disc of moment of inertia
When a round disc of moment of inertia
In the absence of any external torque, angular momentum remains conserved i.e.,