Concepts Of Physics MCQ Edition [Volume 1]
- Exam
- Concepts Of Physics MCQ Edition [Volume 1]
- Subject
- Physics
- Chapter
- Rotational Mechanics
Concepts Of Physics MCQ Edition [Volume 1] · Physics · Rotational Mechanics
Let I_A and I_B denote the moments of inertia of a body about two...
Let and denote the moments of inertia of a body about two axes and , respectively. Axis passes through the body's centre of mass, whereas axis does not.
Options
- AIf , the axes are parallel
- B
- CIf the axes are parallel,
- DIf the axes are not parallel,
Correct answer
C. If the axes are parallel,
Step-by-step solution
According to the parallel axis theorem, the moment of inertia of a body about any axis is equal to the sum of its moment of inertia about a parallel axis passing through its centre of mass and the product of its mass and the square of the perpendicular distance between the two axes.
Let axis pass through the centre of mass and axis be parallel to axis at a perpendicular distance .
Then,
Since axis does not pass through the centre of mass, , which implies .
Therefore, or .
Thus, if the axes are parallel, is always true.
Let axis pass through the centre of mass and axis be parallel to axis at a perpendicular distance .
Then,
Since axis does not pass through the centre of mass, , which implies .
Therefore, or .
Thus, if the axes are parallel, is always true.