Two circular discs of same weight and thickness are made from metals having different densities. Which disc will have the larger rotational inertia about its central axis? A. Disc with larger density B. Disc with smaller density C. Both discs will have same rotational inertia D. None of the above

The correct answer is: A. Disc with larger density.

The rotational inertia of an object is a measure of how difficult it is to change the object’s rotation. It depends on the mass of the object and how the mass is distributed around the axis of rotation.

In this case, the two discs have the same weight and thickness, but they are made from metals with different densities. The density of a material is its mass per unit volume. A material with a higher density has more mass per unit volume, so it will have more inertia.

The disc with the higher density will have more mass per unit area, so it will have more inertia about its central axis.

Option B is incorrect because the disc with the smaller density will have less mass per unit area, so it will have less inertia about its central axis.

Option C is incorrect because the two discs have different densities, so they will have different rotational inertias.

Option D is incorrect because the two discs have different densities, so they will have different rotational inertias.