Question 71 – Rankers Physics

Uncategorized: Practice Problem & Solution

A round disc of moment of inertia $I_2$ about its axis perpendicular to its plane and passing through its centre is placed over another disc of moment of inertia $I_1$ rotating with an angular velocity $\omega$ about the same axis. The final angular velocity of the combination of discs is: (2004)
$\omega$
$\frac{I_1 \omega}{I_1 + I_2}$
$\frac{(I_1 + I_2) \omega}{I_1}$
$\frac{I_2 \omega}{I_1 + I_2}$

Solution Explained:

To solve this problem, we apply the core principles of Uncategorized. Understanding the underlying formula is key to arriving at the correct answer below:

Since no external torque acts on the system, angular momentum is conserved.
Initial angular momentum $L_i = I_1\omega$.
Final angular momentum $L_f = (I_1 + I_2)\omega'$. Equating $L_i$ and $L_f$, we get $\omega' = \frac{I_1\omega}{I_1 + I_2} $.

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