Disc X has radius R and thickness t. Disc Y is made of the same material, has radius 4R and thickness t/4. If their moments of inertia about their symmetry axes are $I_{x}$ and $I_{y}$ , which relation is correct?
Options

Question

Disc X has radius R and thickness t. Disc Y is made of the same material, has radius 4R and thickness t/4. If their moments of inertia about their symmetry axes are $I_{x}$ and $I_{y}$ , which relation is correct?

Options

G1 Physics · Accepted Answer

Mass is proportional to area × thickness. Therefore M(Y)/M(X)=16×(1/4)=4. For a disc, I∝MR², so I(Y)/I(X)=4×(4²)=64. Hence option D.

Disc X has radius R and thickness t. Disc Y is made of the same material, has radius 4R and thickness t/4. If their moments of inertia about their symmetry axes are I x I_{x} I x ​ and I y I_{y} I y ​ , which relation is correct?

Disc X has radius R and thickness t. Disc Y is made of the same material, has radius 4R and thickness t/4. If their moments of inertia about their symmetry axes are I x I_{x} I x and I y I_{y} I y , which relation is correct?