Chapter–6: Work, Energy and Power 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 Two objects of equal mass rest on the opposite pans of an arm balance. Scale will remains balanced, when it is accelerated up or down in a lift.
Reason: Both masses experience unequal fictitious forces in magnitude as well as in direction
(a) (A) (b) (B) (c) (C) (d) (D)
Answer: c
- Assertion: A car accelerates on a horizontal road due to the force exerted by the engine of the car.
Reason: To accelerate a body force is always needed in the direction of required acceleration.
(a) (A) (b) (B) (c) (C) (d) (D)
Answer: d
- Assertion: Centrifugal force acts on a particle because the particle moves on a circle.
Reason: Centrifugal force is a pseudo force.
(a) (A) (b) (B) (c) (C) (d) (D)
Answer: d
- Assertion: If a string moves over a rough massive pulley without slipping, then tension in the string, on both sides of pulley will be different.
Reason: To rotate a massive pulley, there should be net torque acting on the pulley
(a) (A) (b) (B) (c) (C) (d) (D)
Answer: a
- Assertion: Value of frictional force as seen from an inertial frame, for a pair of solids may change if it is observed from a non inertial frame.
Reason: Coefficient of friction m does not depends on frame of reference.
(a) (A) (b) (B) (c) (C) (d) (D)
Answer: d
Q.6 Assertion : When a particle moves in a circle with a uniform speed its acceleration is constant but the velocity changes.
Reason : Angular displacement is not a axial vector.
(1) A (2) B (3) C (4) D
Answer:4
Q.7 Assertion : The total displacement moved by a point located on the periphery of a wheel of radius R in one revolution is 2pR. Wheel is rolling.
Reason : In rolling motion of a wheel, every point on its periphery comes in contact with the surface once in one revolution.
(1) A (2) B (3) C (4) D
Answer:1
Q.8 Assertion : The tendency of skidding or overturning is quadrupled, when a cyclist doubles his speed of turning.
Reason : Angle of bending measured from ground., decreases as velocity of vehicle increases.
(1) A (2) B (3) C (4) D
Answer: 1
Q.9 Assertion : In uniform circular motion speed of particle must be constant.
Reason : In uniform circular motion no force or acceleration is acting on particle acting parallel or in anti parallel to the direction of velocity.
(1) A (2) B (3) C (4) D
Answer:1
Q.10 Assertion : When the direction of motion of a particle moving in a circular path is reversed the direction of radial acceleration still remains the same (at the given point).
Reason : Particle revolves on circular path in any direction such as clockwise or anticlockwise the direction of radial acceleration is always towards the centre of the circular path.
(1) A (2) B (3) C (4) D
Answer:1
Q.11 Assertion : A particle moves along circular path with constant speed then acceleration must be present.
Reason : A particle moves with variable velocity then acceleration must be present.
(1) A (2) B (3) C (4) D
Answer: 1
Q.12 Assertion : For uniform circular motion it is necessary the speed of the particle is constant.
Reason : There is no tangential force or tangential acceleration acting on particle in uniform circular motion.
(1) A (2) B (3) C (4) D
Answer:1
Q.13 Assertion : A car moving on a horizontal road may be thrown out of the road in taking a turn due to lack of proper centripetal force.
Reason : If a particle moves in a circle describing equal angles in equal intervals of time. Then the velocity vector changes its magnitude.
(1) A (2) B (3) C (4) D
Answer: 3
Q.14 Assertion : Acceleration of the particle in uniform circular motion remain constant.
Reason : Velocity of the particle doesn’t change in circular motion.
(1) A (2) B (3) C (4) D
Answer: 4
Q.15 Assertion : A cyclist always bends inwards while negotiating a curve.
Reason : By bending, cyclist lowers his centre of gravity.
(1) A (2) B (3) C (4) D
Answer: 3
Q.16 Assertion : In a uniform circular motion, the linear speed and angular speed of the body are constant.
Reason : A body can move on a circular path without having acceleration.
(1) A (2) B (3) C (4) D
Answer: 3
Q.17 Assertion : The resultant acceleration of an object in circular motion is towards the centre if the speed is constant.
Reason : A vector is necessarily changed if it is rotated through an angle.
(1) A (2) B (3) C (4) D
Answer: 3
Q.8 Assertion : Work done by the centripetal force in moving a body along a circle is always zero.
Reason : In circular motion the displacement of the body is along the force.
(1) A (2) B (3) C (4) D
Answer: 3
Q.18 Assertion : Centripetal and centrifugal forces cancel each other.
Reason : This is because they are always equal and opposite.
(1) A (2) B (3) C (4) D
Answer: 4
Q.19 Assertion : A cyclist bends inwards from his vertical position, while turning to secure the necessary centripetal force.
Reason : Friction between the tyres and road provides him the necessary centripetal force.
(1) A (2) B (3) C (4) D
Answer: 3
Q.20 Assertion : Work done by centripetal force is zero.
Reason : Centripetal force acts perpendicular to the displacement.
(1) A (2) B (3) C (4) D
Answer:1