JEE MainPhysicsRotational Motion
A steering wheel is constructed from a thin uniform outer ring of mass M and radius L , and four mutually perpendicular spokes. The spokes are identical uniform solid cylinders, each of radius R and length L , connecting the center of the wheel to the outer ring. The total mass of the four spokes combined is also M . The total moment of inertia of the wheel about its central axis (perpendicular to the plane of the wh
Options
- A4 3 M L²
- B1 4 M R² + 4 3 M L²
- CM R² + 7 3 M L²
- D1 2 M R² + M L²
Correct answer
B. 1 4 M R² + 4 3 M L²
Step-by-step solution
The total moment of inertia of the wheel is the sum of the moment of inertia of the outer ring and the four spokes. For the thin uniform outer ring of mass M and radius L , the moment of inertia about the central axis is: I_ ring = M L² The four spokes have a total mass of M , so each spoke has a mass m = M 4 . The central axis is perpendicular to the length of each spoke and passes through one of its ends. Using the parallel axis theorem, the moment of inertia of one spoke about this axis is: I_ spoke = I_ cm + m