Q7.11 Torques of equal magnitude are applied to a hollow cylinder and a solid sphere, both
having the same mass and radius. The cylinder is free to rotate about its standard
axis of symmetry, and the sphere is free to rotate about an axis passing through its
centre. Which of the two will acquire a greater angular speed after a given time.
The moment of inertia of hollow cylinder is given by
And the moment of inertia of solid cylinder is given by :
We know that :
Let the torque for hollow cylinder be and for solid cylinder let it be .
According to the question :
So we can write the ratio of the angular acceleration of both the objects.
Now for angular velocity,
Clearly, the angular velocity of the solid sphere is more than the angular velocity of the hollow sphere. (As the angular acceleration of solid sphere is greater).