A circular disc is to be made by using iron and aluminium so that it acquired maximum moment of inertia about geometrical axis. It is possible with
- aluminium at interior and iron surround to it
- iron at interior and aluminium surround to it
- using iron and aluminium layers in alternate order
- sheet of iron is used at both external surface and aluminium sheet as internal layers.
Answer
(1) aluminium at interior and iron surround to it
Solution
I = m r2 mass placed farther from the axis contributes more to I.
Density of iron > density of aluminium
The heavier material (iron) should be at the outer part (large r) and aluminium in the interior.
Aluminium at interior and iron surrounding it gives the maximum moment of inertia.
Answer: (1)