Chapter–7: System of Particles and Rotational Motion Assertion Reason
These questions of two statements each, printed as Assertion and Reason. While answering these Questions you are required to choose any one of the following four responses.
(A) If both Assertion & Reason are true & the Reason is a correct explanation of the Assertion.
(B) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
(C) If Assertion is true but the Reason is false.
(D) If Assertion & Reason both are false.
Assertion-Reason Questions
- Assertion (A): The angular momentum of a particle about a point is zero if the particle is at rest.
Reason (R): Angular momentum is given by the cross product of the position vector and linear momentum vector.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): The torque acting on a particle is zero if the force acting on it is parallel to its position vector.
Reason (R): Torque is given by the cross product of the position vector and the force vector.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): A rigid body can have both rotational and translational motion simultaneously.
Reason (R): The motion of a rigid body can be described by the motion of its center of mass and its rotation about an axis.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): The moment of inertia of a body depends on the distribution of mass around the axis of rotation.
Reason (R): Moment of inertia is a measure of an object’s resistance to changes in its rotational motion.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): A body in pure rotational motion about a fixed axis has zero translational kinetic energy.
Reason (R): In pure rotational motion, every point of the body moves in a circular path.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): For a rigid body in rotational motion, all points on the body have the same angular velocity.
Reason (R): Angular velocity is a measure of the rate of change of angular displacement.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): A uniform disc and a uniform ring of the same radius have different moments of inertia about their central axis.
Reason (R): Moment of inertia depends on the mass distribution relative to the axis of rotation.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): The angular acceleration of a body is directly proportional to the net external torque acting on it.
Reason (R): Newton’s second law for rotation states that torque is equal to the moment of inertia times angular acceleration.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): In a non-inertial frame of reference, pseudo forces must be considered in analyzing the motion of particles.
Reason (R): Pseudo forces arise due to the acceleration of the non-inertial frame itself.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): In uniform circular motion, the centripetal force does no work on the particle.
Reason (R): Work is defined as the dot product of force and displacement vectors.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): A particle in circular motion with a constant speed has a changing velocity.
Reason (R): Velocity is a vector quantity and depends on both magnitude and direction.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): In rotational motion, the angular velocity vector is always perpendicular to the plane of rotation.
Reason (R): The direction of the angular velocity vector is determined by the right-hand rule.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): In the absence of external forces, the total linear momentum of a system of particles is conserved.
Reason (R): The law of conservation of linear momentum states that the total momentum of an isolated system remains constant.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): In a perfectly inelastic collision, the kinetic energy of the system is not conserved.
Reason (R): In a perfectly inelastic collision, the colliding bodies stick together and move as one mass.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): The center of mass of a two-particle system lies closer to the more massive particle.
Reason (R): The center of mass is the weighted average position of all the masses in the system.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): For a system of particles, the internal forces do not affect the motion of the center of mass.
Reason (R): Internal forces occur in equal and opposite pairs, canceling each other out.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): A particle moving in a circular path with uniform speed has a constant centripetal force acting on it.
Reason (R): Centripetal force is responsible for the change in direction of the particle’s velocity.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): The angular momentum of a rigid body remains constant if no external torque acts on it.
Reason (R): The conservation of angular momentum states that in the absence of external torque, the total angular momentum of a system remains constant.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): For a rolling object, the point of contact with the ground is instantaneously at rest.
Reason (R): Rolling motion is a combination of rotational and translational motion.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): The radius of gyration of a body depends on the axis of rotation.
Reason (R): Radius of gyration is the distance from the axis at which the entire mass of the body can be assumed to be concentrated to give the same moment of inertia.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): The total kinetic energy of a rolling object is the sum of its translational and rotational kinetic energies.
Reason (R): Kinetic energy in rolling motion includes both linear and angular components.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
- Assertion (A): The center of mass of a system of particles can lie outside the physical boundaries of the system.
Reason (R): The center of mass is the point where the total mass of the system can be considered to be concentrated for analysis of motion.- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answers to Assertion-Reason Questions
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Directions: Read the following questions and choose
(A) If both the statements are true and statement-2 is the correct explanation of statement-1.
(B) If both the statements are true but statement-2 is not the correct explanation of statement-1.
(C) If statement-1 is True and statement-2 is False.
(D) If statement-1 is False and statement-2 is True.
- Statement-1: In oblique elastic collision of two bodies, momentum is not conserved along a line making non-zero angle with line of impact.
Statement-2: In oblique collision of same masses, one at rest initially, bodies go at right angle to each other after collision.
(a) (A) (b) (B) (c) (C) (d) (D)
Answer: d
- Statement-1: Area per unit mass of force-time graph gives change in velocity.
Statement-2: An impulse changes the momentum of a body by then
(a) (A) (b) (B) (c) (C) (d) (D)
Answer: a
- Statement-1: Two balls are thrown simultaneously in air. The acceleration of centre of mass of the two balls while in air depends on the masses of the two balls.
Statement-2: The acceleration of centre of mass is given by
(a) (A) (b) (B) (c) (C) (d) (D)
Answer: d
Chapter–6: Work, Energy and Power Assertion Reason
Chapter–8: Gravitation Assertion Reason