Moment of inertia of a circular wire of mass M and radius R about its ...
A circular wire behaves like a ring. By perpendicular axes theorem,
ID + ID = 1/2 MR2
Therefore,
1/4 MR2.
Moment of inertia of a circular wire of mass M and radius R about its ...
Understanding Moment of Inertia
The moment of inertia (I) is a measure of an object's resistance to angular acceleration about a particular axis. For a circular wire, it depends on both its mass and the distribution of that mass relative to the axis of rotation.
Moment of Inertia of a Circular Wire
To find the moment of inertia of a circular wire about its diameter, we can use principles of integration or known results from physics.
Key Concepts
- Mass Distribution: The circular wire has a uniform mass distribution along its length.
- Axis of Rotation: We are interested in the axis that runs through the diameter of the circle.
Calculation Details
- The moment of inertia for a thin circular wire about an axis through its center and perpendicular to its plane (the z-axis) is given by the formula I = MR^2.
- By using the perpendicular axis theorem, we can derive the moment of inertia about the diameter (x or y-axis). The perpendicular axis theorem states that for a planar body:
I_z = I_x + I_y, where I_z is the moment of inertia about the axis perpendicular to the plane, and I_x and I_y are about the two perpendicular axes in the plane.
- For a circular wire, I_z = MR^2. Since I_x = I_y for symmetry, we have:
I_z = I_x + I_y = 2I_x.
Thus, I_x = I_z / 2 = MR^2 / 2.
Conclusion
Therefore, the moment of inertia of a circular wire of mass M and radius R about its diameter is:
Answer: I = 1/2 MR^2
This confirms that option 'B' is correct.