# NCERT Physics Class 11 Exemplar Ch 7 System of Particles and Rotational Motion Part 1 (For CBSE, ICSE, IAS, NET, NRA 2022)

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## MCQs Type Questions

Q. 1. For which of the following does the center of mass lie outside the body?

(a) A pencil

(b) A shotput

(c) A dice

(d) A bangle

Answer: d

Q. 2. Which of the following points is the likely position of the center of mass of the system shown in Fig. ? Hollow Sphere of Air

(a) A

(b) B

(c) C

(d) D

Answer: c

Q. 3. A particle of mass m is moving in plane with a uniform velocity v with its trajectory running parallel -axis and intersecting z-axis at z = a (Fig.) . The change in its angular momentum about the origin as it bounces elastically from a wall is: Velocity

(a)

(b)

(c)

(d)

Answer: The initial velocity is and, after reflection from the wall, the final velocity is . The trajectory is described as

Hence the change in angular momentum is

Hence the answer is (b) .

Q. 4 When a disc rotates with uniform angular velocity, which of the following is not true?

(a) The sense of rotation remains same.

(b) The orientation of the axis of rotation remains same.

(c) The speed of rotation is non-zero and remains same.

(d) The angular acceleration is non-zero and remains same.

Answer: d