Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
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 IAI_A and IBI_B denote the moments of inertia of a body about two axes AA and BB, respectively. Axis AA passes through the body's centre of mass, whereas axis BB does not.

Options

  1. AIf IA<IBI_A < I_B, the axes are parallel
  2. BIA<IBI_A < I_B
  3. CIf the axes are parallel, IA<IBI_A < I_B
  4. DIf the axes are not parallel, IA≥IBI_A \geq I_B

Correct answer

C. If the axes are parallel, IA<IBI_A < I_B

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 AA pass through the centre of mass and axis BB be parallel to axis AA at a perpendicular distance dd.

Then, IB=IA+Md2I_B = I_A + Md^2

Since axis BB does not pass through the centre of mass, d≠0d \neq 0, which implies Md2>0Md^2 > 0.

Therefore, IB>IAI_B > I_A or IA<IBI_A < I_B.

Thus, if the axes are parallel, IA<IBI_A < I_B is always true.
Practice Rotational Mechanics on Quantrex Academy →

More from Rotational Mechanics

A wheel revolves about its axis with a uniform angular acceleration. Beginning from rest… Concepts Of Physics MCQ Edition [Volume 1]Starting from rest, a wheel is uniformly accelerated at 4 rad/s^2 for 10 seconds.… Concepts Of Physics MCQ Edition [Volume 1]Determine the angular velocity of a body rotating with an acceleration of 2 rev/s^2 as it… Concepts Of Physics MCQ Edition [Volume 1]A body rotates about a fixed axis with an angular acceleration of one… Concepts Of Physics MCQ Edition [Volume 1]A disc of radius 10 cm rotates about its axis with an angular speed of 20 rad/s .… Concepts Of Physics MCQ Edition [Volume 1]A disc of radius 10 cm rotates about its axis with an angular speed of 20 rad/s .… Concepts Of Physics MCQ Edition [Volume 1]A disc rotates about its axis with a uniform angular acceleration of 4 rad/s^2 .… Concepts Of Physics MCQ Edition [Volume 1]A block is suspended from a string wrapped on a disc of radius 20 cm , which is free to… Concepts Of Physics MCQ Edition [Volume 1] Full Rotational Mechanics list All Concepts Of Physics MCQ Edition [Volume 1] PYQs