Please refer to MCQ Questions Chapter 7 Systems of Particles and Rotational Motion Class 11 Physics with answers provided below. These multiple-choice questions have been developed based on the latest NCERT book for class 11 Physics issued for the current academic year. We have provided MCQ Questions for Class 11 Physics for all chapters on our website. Students should learn the objective based questions for Chapter 7 Systems of Particles and Rotational Motion in Class 11 Physics provided below to get more marks in exams.

**Chapter 7 Systems of Particles and Rotational Motion MCQ Questions**

Please refer to the following **Chapter 7 Systems of Particles and Rotational Motion MCQ Questions Class 11 Physics** with solutions for all important topics in the chapter.

**MCQ Questions Answers for Chapter 7 Systems of Particles and Rotational Motion Class 11 Physics**

** Question. A disc is given a linear velocity on a rough horizontal surface then its angular momentum is**(a) conserved about COM only

(b) conserved about the point of contact only

(c) conserved about all the points

(d) not conserved about any point.

**Answer**

B

**Question.** Four particles of masses m_{1},m_{2},m_{3} and m_{4} are placed at the vertices A,B,C and D as respectively of a square shown. The COM of the system will lie at diagonal AC if

(a) m_{1} = m_{3}

(b) m_{2} = m_{4}

(c) m_{1} = m_{2}

(d) m_{3 }= m_{4}

**Answer**

B

**Question.****Angular momentum of a system of a particles changes, when**

(a) force acts on a body

(b) torque acts on a body

(c) direction of velocity changes

(d) None of these

**Answer**

B

**Question.** Two spheres A and B of masses m and 2m and radii 2R and R respectively are placed in contact as shown. The COM of the system lies

(a) inside A

(b) inside B

(c) at the point of contact

(d) None of these

**Answer**

C

**Question.** Moment of inertia of a circular wire of mass M and radius R about its diameter is

(a) MR^{2}/2

(b) MR^{2}

(c) 2MR^{2}

(d) MR^{2}/4.

**Answer**

A

**Question.** A solid sphere is rotating in free space. If the radius of the sphere is increased keeping mass same which one of the following will not be affected ?

(a) Angular velocity

(b) Angular momentum

(c) Moment of inertia

(d) Rotational kinetic energy

**Answer**

B

**Question.****A body cannot roll without slipping on a**(a) rough horizontal surface

(b) smooth horizontal surface

(c) rough inclined surface

(d) smooth inclined surface

**Answer**

D

**Question.****Angular momentum is**

(a) a polar vector

(b) an axial vector

(c) a scalar

(d) None of these

**Answer**

B

**Question.** A solid cylinder of mass m & radius R rolls down inclined plane without slipping. The speed of its C.M. when it reaches the bottom is

**Answer**

B

**Question.** If a running boy jumps on a rotating table, which of the following is conserved?

(a) Linear momentum

(b) K.E

(c) Angular momentum

(d) None of these

**Answer**

C

**Question.****The ratio of moment of inertia of circular ring & circular disc having the same mass & radii about on axis passing the c.m & perpendicular to plane is**

(a) 1 : 1

(b) 2 : 1

(c) 1 : 2

(d) 4 : 1

**Answer**

B

**Question.** A mass m is moving with a constant velocity along a line parallel to the x-axis, away from the origin. Its angular momentum with respect to the origin

(a) is zero

(b) remains constant

(c) goes on increasing

(d) goes on decreasing.

**Answer**

B

**Question.** A gymnast takes turns with her arms & legs stretched. When she pulls her arms & legs in

(a) the angular velocity decreases

(b) the moment of inertia decreases

(c) the angular velocity stays constant

(d) the angular momentum increases

**Answer**

B

**Question.****One solid sphere A and another hollow sphere B are of same mass and same outer radii. Their moment of inertia about their diameters are respectively I _{A} and I_{B} Such that**

where d_{A} and d_{B} are their densities

**Answer**

A

**Question.** A smooth sphere A is moving on a frictionless horizontal plane with angular speed w and centre of mass velocity v. It collides elastically and head on with an identical sphere B at rest. Neglect friction everywhere. After the collision, their angular speeds are ϖA and ϖB, respectively. Then

(a) ϖ_{A}< ϖ_{B}

(b) ϖ_{A}= ϖ_{B}

(c) ϖ_{A}= ϖ

(d) ϖ_{B}= ϖ

**Answer**

C

**Question.****Angular momentum is**

(a) moment of momentum

(b) product of mass and angular velocity

(c) product of M.I. and velocity

(d) moment of angular motion

**Answer**

A

**Question.****A particle moves in a circle of radius 4 cm clockwise at constant speed 2 cm s ^{–1} . If xˆ and ˆy are unit acceleration vectors along X and Y respectively (in cm s^{–2}), the acceleration of the particle at the instant half way between P and Q is given by**

(a) -4(x^{ˆ} + y^{ˆ})

(b) 4(x^{ˆ} + y^{ˆ})

(c) – (x^{ˆ} + y^{ˆ}) /√2

(d) (x^{ˆ} – y^{ˆ}) / 4

**Answer**

C

**Question.****The angular momentum of a system of particle is conserved**

(a) when no external force acts upon the system

(b) when no external torque acts upon the system

(c) when no external impulse acts upon the system

(d) when axis of rotation remains same

**Answer**

B

**Question.** A hollow sphere is held suspended. Sand is now poured into it in stages.

**The centre of gravity of the sphere with the sand**

(a) rises continuously

(b) remains unchanged in the process

(c) First rises and then falls to the original position

(d) First falls and then rises to the original position

**Answer**

D

**Question.** A particle of mass m is observed from an inertial frame of reference and is found to move in a circle of radius r with a uniform speed v. The centrifugal force on it is

(a) mv^{2}/r towards the centre

(b) mv^{2}/r away from the centre

(c) mv^{2}/r along the tangent through the particle

(d) zero

**Answer**

D

**Question.****A block Q of mass M is placed on a horizontal frictionless surface AB and a body P of mass m is released on its frictionless slope. As P slides by a length L on this slope of inclination q, the block Q would slide by a distance**

(a) (m/M) L cos θ

(b) m L/(M + m)

(c) (M + m)/(m L cos θ)

(d) (m L cos θ) / (m + M)

**Answer**

D

**Question.** A solid sphere and a hollow sphere of the same material and of same size can be distinguished without weighing

(a) by determining their moments of inertia about their coaxial axes

(b) by rolling them simultaneously on an inclined plane

(c) by rotating them about a common axis of rotation

(d) by applying equal torque on them

**Answer**

B

**Question**. A circular disc X of radius R is made from an iron plate of thickness t, and another disc Y of radius 4R is made from an iron plate of thickness t/4. Then the relation between the moment of inertia I_{X} and I_{Y} is

(a) Ι_{Y} = 32 Ι_{X}

(b) Ι_{Y} = 16 Ι_{X}

(c) Ι_{Y} = Ι_{X}

(d) Ι_{Y} = 64 Ι_{X}

**Answer**

D

**Question.****A stick of length L and mass M lies on a frictionless horizontal surface on which it is free to move in any way. A ball of mass m moving with speed v collides elastically with the stick as shown in fig.**

**If after the collision ball comes to rest, then what should be** **the mass of the ball?**

(a) m = 2 M

(b) m = M

(c) m = M/2

(d) m = M/4

**Answer**

D

**Question.****A flywheel rotates about an axis. Due to friction at the axis, it experiences an angular retardation proportional to its angular velocity. If its angular velocity falls to half while it makes n rotations, how many more rotations will it make before coming to rest?**

(a) 2n

(b) n

(c) n/2

(d) n/3

**Answer**

B

**Question.****A solid cylinder of mass 20 kg rotates about its axis with angular speed 100 rad/s. The radius of the cylinder is 0.25 m. The K.E. associated with the rotation of the cylinder is**

(a) 3025 J

(b) 3225 J

(c) 3250 J

(d) 3125 J

**Answer**

D

**Question.** A raw egg and a hard boiled egg are made to spin on a table with the same angular momentum about the same axis. The ratio of the time taken by the two to stop is

(a) = 1

(b) < 1

(c) > 1

(d) None of these

**Answer**

B

**Question.****What is the moment of inertia of a solid sphere of density r and radius R about its diameter?**

**Answer**

C

**Question.****Two particles A and B, initially at rest, moves towards each other under a mutual force of attraction. At the instant when the speed of A is v and the speed of B is 2 v, the speed of centre of mass is**

(a) zero

(b) v

(c) 1.5 v

(d) 3 v

**Answer**

A

**Question.****A body having moment of inertia about its axis of rotation equal to 3 kg-m ^{2} is rotating with angular velocity equal to 3 rad/s. Kinetic energy of this rotating body is the same as that of a body of mass 27 kg moving with a speed of**

(a) 1.0 m/s

(b) 0.5 m/s

(c) 1.5 m/s

(d) 2.0 m/s

**Answer**

A

**Question.****Point masses 1, 2, 3 and 4 kg are lying at the points (0, 0, 0), (2, 0, 0), (0, 3, 0) and (–2, –2, 0) respectively. The moment of inertia of this system about X-axis will be**

(a) 43 kg –m^{2}

(b) 34 kg–m^{2}

(c) 27 kg – m^{2}

(d) 72 kg – m^{2}

**Answer**

A

**Question.**** A particle moves in a circle of radius 0.25 m at two revolutions per second. The acceleration of the particle in metre per second ^{2} is**

(a) π

_{2}

(b) 8π

_{2}

(c) 4π

_{2}

(d) 2π

_{2}

**Answer**

C

**Question.** Centre of mass of the earth and the moon system lies

(a) closer to the earth

(b) closer to the moon

(c) at the mid-point of line joining the earth and the moon

(d) cannot be predicted

**Answer**

A

**Question.****Moment of inertia does not depend upon**(a) distribution of mass

(b) axis of rotation

(c) point of application of force

(d) None of these

**Answer**

C

**Question.** The radius of gyration of a body about an axis at a distance 6 cm from its centre of mass is 10 cm. Then, its radius of gyration about a parallel axis through its centre of mass will be

(a) 80 cm

(b) 8 cm

(c) 0.8 cm

(d) 80 m

**Answer**

B

**Question.** A rod of length L is pivoted at one end and is rotated with a uniform angular velocity in a horizontal plane. Let T_{1} and T_{2} be the tensions at the points L/4 and 3L/4 away from the pivoted end. Then

(a) T_{1} > T_{2}

(b) T_{2 }> T_{1}

(c) T_{1} – T_{2}

(d) the relation between T_{1} and T_{2} depends on whether the rod rotates clockwise and anticlockwise.

**Answer**

A

**Question.** **15. A particles performing uniform circular motion. Its angular frequency is doubled and its kinetic energy halved, then the new angular momentum is**

(a) L.4

(b) 2 L

(c) 4 L

(d) L/2

**Answer**

A

** Question. A body is projected from ground with some angle to the horizontal. The angular momentum about the initial position will**(a) decrease

(b) increase

(c) remains same

(d) first increase then decrease

**Answer**

B

**Question.** A couple is acting on a two particle systems. The resultant motion will be

(a) purely rotational motion

(b) purely linear motion

(c) both a and b

(d) None of these

**Answer**

A

**Question.****A ball tied to a string is swung in a vertical circle. Which of the following remains constant?**

(a) tension in the string

(b) speed of the ball

(c) centripetal force

(d) earth’s pull on the ball

**Answer**

D

**Question.** A simple pendulum is vibrating with angular amplitude of 90° as shown in figure.

**For what value of θ is the acceleration directed****(i) vertically upwards(ii) horizontally(iii) vertically downwards**

**Answer**

A

**Question.** Analogue of mass in rotational motion is

(a) moment of inertia

(b) angular momentum

(c) gyration

(d) None of these

**Answer**

A

**Question.** Two rings of radius R and nR made up of same material have the ratio of moment of inertia about an axis passing through centre as 1 : 8. The value of n is

(a) 2

(b) 2√2

(c) 4

(d) 1/2

**Answer**

A

**Question.** Moment of inertia does not depend upon

(a) angular velocity of body

(b) shape and size

(c) mass

(d) position of axis of rotation

**Answer**

A

**Question.** A mass is tied to a string and rotated in a vertical circle, the minimum velocity of the body at the top is

**Answer**

A

**Question.** A particle is confined to rotate in a circular path decreasing linear speed, then which of the following is correct?

(a) L^{→ }(angular momentum) is conserved about the centre

(b) only direction of angular momentum L^{→ }is conserved

(c) It spirals towards the centre

(d) its acceleration is towards the centre.

**Answer**

B

**Question.** A cylinder rolls down an inclined plane of inclination 30°, the acceleration of cylinder is

(a) g/3

(b) g

(c) g/2

(d) 2g/3

**Answer**

A

**Question.** A particle of mass m is moving in a plane along a circular path of radius r. Its angular momentum about the axis of rotation is L. The centripetal force acting on the particle is

(a) L^{2} /mr

(b) L^{2} m/r

(c) L^{2} /m r^{3}

(d) L^{2} /m r^{2}

**Answer**

C

**Question.** A uniform bar of mass M and length L is horizontally suspended from the ceiling by two vertical light cables as shown. Cable A is connected 1/4th distance from the left end of the bar. Cable B is attached at the far right end of the bar. What is the tension in cable A?

(a) 1/4 Mg

(b) 1/3 Mg

(c) 2/3 Mg

(d) 3/4 Mg

**Answer**

C

**Question.** A small disc of radius 2 cm is cut from a disc of radius 6 cm. If the distance between their centres is 3.2 cm, what is the shift in the centre of mass of the disc?

(a) 0.4 cm

(b) 2.4 cm

(c) 1.8 cm

(d) 1.2 cm

**Answer**

A

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