back to directory
NEET PHYSICSRotational motionMedium

Question

Two rotating bodies AA and BB of masses mm and 2m2m with moments of inertia IAI_A and IBI_B (IB>IAI_B > I_A) have equal kinetic energy of rotation. If LAL_A and LBL_B be their angular momenta respectively, then:

A

LA=LB2L_A = \frac{L_B}{2}

B

LA=2LBL_A = 2L_B

C

LB>LAL_B > L_A

D

LA>LBL_A > L_B

Step-by-Step Solution

The rotational kinetic energy (KK) is related to angular momentum (LL) and moment of inertia (II) by the relation K=L22IK = \frac{L^2}{2I}. Given that the kinetic energies of rotation are equal: KA=KBK_A = K_B. LA22IA=LB22IB\frac{L_A^2}{2I_A} = \frac{L_B^2}{2I_B} Rearranging the terms, we get: LB2LA2=IBIA\frac{L_B^2}{L_A^2} = \frac{I_B}{I_A} It is given that IB>IAI_B > I_A, so the ratio IBIA>1\frac{I_B}{I_A} > 1. Therefore, LB2LA2>1    LB2>LA2    LB>LA\frac{L_B^2}{L_A^2} > 1 \implies L_B^2 > L_A^2 \implies L_B > L_A.

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from Rotational motion. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

PHYSICSRotational motionrotatingbodiesmassesmomentsinertia

More Rotational motion Questions

View all

From a circular ring of mass $M$ and radius $R$, an arc corresponding to a $90^\circ$ sector is removed. The moment of inertia of the remaining part of the ring about an axis passing through the centre of the ring and perpendicular to the plane of the ring is $K$ times $MR^2$. The value of $K$ will be:

A.$\frac{1}{4}$
B.$\frac{1}{8}$
C.$\frac{3}{4}$
D.$\frac{7}{8}$
MediumSolve

The moment of inertia of a uniform circular disc of radius $R$ and mass $M$ about an axis touching the disc at its edge and normal to the disc is:

A.$MR^2$
B.$\frac{2}{5}MR^2$
C.$\frac{3}{2}MR^2$
D.$\frac{1}{2}MR^2$
EasySolve

A solid cylinder of mass $2 \text{ kg}$ and radius $4 \text{ cm}$ is rotating about its axis at the rate of $3 \text{ rpm}$. The torque required to stop after $2\pi$ revolutions is:

A.$2 \times 10^6 \text{ N-m}$
B.$2 \times 10^{-6} \text{ N-m}$
C.$2 \times 10^{-3} \text{ N-m}$
D.$12 \times 10^{-4} \text{ N-m}$
MediumSolve

Three identical spherical shells, each of mass $m$ and radius $r$ are placed as shown in the figure. Consider an axis $XX'$, which is touching two shells and passing through the diameter of the third shell. The moment of inertia of the system consisting of these three spherical shells about the $XX'$ axis is:

A.$\frac{11}{5}mr^2$
B.$3mr^2$
C.$\frac{16}{5}mr^2$
D.$4mr^2$
MediumSolve

A solid cylinder of mass $3 \text{ kg}$ is rolling on a horizontal surface with a velocity of $4 \text{ ms}^{-1}$. It collides with a horizontal spring of force constant $200 \text{ Nm}^{-1}$. The maximum compression produced in the spring will be:

A.0.5 m
B.0.6 m
C.0.7 m
D.0.2 m
MediumSolve

The moment of inertia of a thin rod about an axis passing through its mid-point and perpendicular to the rod is $2400\text{ g cm}^2$. The length of the $400\text{ g}$ rod is nearly:

A.$17.5\text{ cm}$
B.$20.7\text{ cm}$
C.$72.0\text{ cm}$
D.$8.5\text{ cm}$
EasySolve

A solid sphere is in rolling motion. In rolling motion, a body possesses translational kinetic energy ($K_t$) as well as rotational kinetic energy ($K_r$) simultaneously. The ratio $K_t : (K_t + K_r)$ for the sphere will be:

A.7:10
B.5:7
C.10:7
D.2:5
MediumSolve

An energy of $484 \text{ J}$ is spent in increasing the speed of a flywheel from $60 \text{ rpm}$ to $360 \text{ rpm}$. The moment of inertia of the flywheel is:

A.$0.7 \text{ kg-m}^2$
B.$3.22 \text{ kg-m}^2$
C.$30.8 \text{ kg-m}^2$
D.$0.07 \text{ kg-m}^2$
MediumSolve

This neet physics practice question is part of the TopperSquare free question bank. TopperSquare offers 15,000+ chapter-wise NEET MCQs across Physics, Chemistry, and Biology with detailed step-by-step explanations, full mock tests, NEET PYQs (2010–2024), and an AI-powered performance analytics dashboard. browse all neet practice questions → · practice physics sets →