NEET Physics: rigid body rotation and equations of rotational motion Practice Questions

Correct answer: A — It must be zero

Angular acceleration (α) is the rate of change of angular velocity (ω). If ω is constant, then α= 0.

Correct answer: A — Torque

According to rotational dynamics, the relationship is τ= Iα, where τ is torque, I is moment of inertia, and α is angular acceleration. Thus, α= τ/I. If torque (τ) and moment of inertia (I) are constant, α is constant, but α is directly proportional to τ and inversely proportional to I.

Correct answer: C — Change in rotational motion (angular acceleration)

Moment of inertia (I) is the rotational analogue to mass and measures an object's resistance to changes in its rotational motion.

Correct answer: D — The angular acceleration is zero.

According to the rotational equivalent of Newton's second law (τ= Iα), if the net torque (τ) is zero, then the angular acceleration (α) must also be zero, assuming the moment of inertia (I) is finite.

Correct answer: B — Rθ

The linear distance (arc length) covered by a particle moving along a circular path is given by the formula s = Rθ, where R is the radius and θ is the angle subtended in radians.

Correct answer: C — Force

Torque is the rotational equivalent of force; it measures the tendency of a force to cause rotation.

Correct answer: A — Angular acceleration

Linear acceleration (a⃗) relates to the change in linear velocity over time. Angular acceleration (α⃗) relates to the change in angular velocity over time. Angular acceleration is the rotational equivalent of linear acceleration.

Correct answer: B — It increases

Rotational kinetic energy is proportional to the moment of inertia (KEᵣₒₜ = 1/2 I ω²). If I increases and ω is constant, the kinetic energy increases.

Correct answer: C — Torque

The rotational equivalent of Newton's second law (F=ma) is τ= dL/dt, where τ is torque and L is angular momentum.

Correct answer: D — The measure of rotational inertia

The moment of inertia (I) is the rotational analog of mass. It quantifies the resistance of a body to changes in its rotational motion (angular acceleration).

Correct answer: A — Zero

According to Newton's second law for rotation, Torque (τ) equals the rate of change of angular momentum (τ= dL/dt). If the angular velocity is constant, the angular momentum is constant, meaning the net external torque must be zero.

Correct answer: D — τ= Iα

The rotational equivalent of F=ma is τ= Iα, where τ is the net torque, I is the moment of inertia, and α is the angular acceleration.

Correct answer: D — Particle B

Moment of inertia depends on the mass distribution relative to the axis of rotation. Since particle B has a larger radius (and presumably larger mass distribution spread out), its moment of inertia will be larger than particle A, assuming similar mass distributions or if radius difference dominates.