NEET Physics Systems of Particles and Rotational Motion MCQs Set A

Question.  When a disc rotates with uniform angular velocity, which of the following is not true?
(a) The angular acceleration is non-zero and remains same
(b) The speed of rotation is non-zero and remains same
(c) The orientation of the axis of rotation remains same
(d) The sense of rotation remains same

Answer: A

Question.   In problem-5, the CM of the plate is now in the following quadrant of x-y plane.
(a) III
(b) IV
(c) II
(d) I

Answer: A

Question.  The ratio of the accelerations for a solid sphere (mass ‘m’ and radius ‘R’) rolling down an incline of angle ‘q’ without slipping and slipping down the incline without rolling is :
(a) 5 : 7
(b) 2 : 3
(c) 2 : 5
(d) 7 : 5

Answer: A

Question.  A solid cylinder of mass 50 kg and radius 0.5 m is free to rotate about the horizontal axis. A massless string is wound round the cylinder with one end attached to it and other hanging freely. Tension in the string required to produce an angular acceleration of 2 revolutions s^{– 2} is
(a) 157 N
(b) 78.5 N
(c) 50 N
(d) 25 N

Answer: A

Question.   An automobile moves on a road with a speed of 54 km h^-1. The radius of its wheels is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3 kg m². If the vehicle is brought to rest in 15s, the magnitude of average torque transmitted by its brakes to the wheel is:
(a) 6.66 kg m2 s^-2
(b) 10.86 kg m2 s^-2
(c) 8.58 kg m2 s^-2
(d) 2.86 kg m2 s^-2

Answer: A

Question.  A disk and a sphere of same radius but different masses roll off on two inclined planes of the same altitude and length. Which one of the two objects gets to the bottom of the plane first ?
(a) Sphere
(b) Disk
(c) Both reach at the same time
(d) Depends on their masses

Answer: A

Question.  A uniform circular disc of radius 50 cm at rest is free to turn about an axis which is perpendicular to its plane and passes through its centre. It is subjected to a torque which produces a constant angular acceleration of 2.0 rad s–2. Its net acceleration in ms^–2 at the end of 2.0s is approximately :
(a) 8.0
(b) 7.0
(c) 6.0
(d) 3.0

Answer: A

Question.  From a disc of radius R and mass M, a circular hole of diameter R, whose rim passes through the centre is cut. What is the moment of inertia of the remaining part of the disc about a perpendicular axis, passing through the centre?
(a) 13 MR²/32
(b) 9 MR²/32
(c) 15 MR²/32
(d) 11 MR²/32

Answer: A

Question.  Which of the following statements are correct ?
(A) Centre of mass of a body always coincides with the centre of gravity of the body
(B) Centre of mass of a body is the point at which the total gravitational torque on the body is zero
(C) A couple on a body produce both translational and rotation motion in a body
(D) Mechanical advantage greater than one means that small effort can be used to lift a large load
(a) (B) and (D)
(b) (B) and (C)
(c) (A) and (B)
(d) (C) and (D)

Answer: A