Here, you will get Class 11 Physics MCQ of Chapter 7 System Of Particles And Rotational Motion for cracking JEE and NEET/AIIMS. By solving these MCQs of Class 11 Physics Chapter 7 System Of Particles And Rotational Motion, you will get the confidence to crack JEE or NEET. Practice **MCQ Questions for Class 11 Physics** with Answers on a daily basis and score well in exams.

## System Of Particles And Rotational Motion Class 11 MCQs Questions with Answers

**For an ideal-step-down transformer, the quantity which is constant for both the coils is**

(a) current in the coils

(b) voltage across the coils

(c) resistance of coils

(d) power in the coils

Answer: (d) power in the coils

**Calculate the M.I. of a thin uniform ring about an axis tangent to the ring and in a plane of the ring, if its M.I. about an axis passing through the centre and perpendicular to plane is 4 kg m².**

(a) 12 kg m²

(b) 3 kg m²

(c) 6 kg m²

(d) 9 kg m²

Answer: (c) 6 kg m²

**The centre of mass of a body**

(a) lies always on the surface of the body

(b) lies always inside the body

(c) may lie within, outside on the surface of the body

(d) lies always outside the body

Answer: (a) lies always on the surface of the body

**In a series LCR circuit the voltage across an inductor, capacitor and resistor are 20 V, 20 V and 40 V respectively. The phase difference between the applied voltage and the current in the circuit is**

(a) 30°

(b) 45°

(c) 60°

(d) 0°

Answer: (d) 0°

**In rotation of a rigid body about a fixed axis, every …A…of the body moves in a …B…, which lies in a plane …C… to the axis and has its centre on the axis. Here, A, B and C refer to**

(a) particle, circle and perpendicular

(b) particle perpendicular and perpendicular

(c) circle, particle and perpendicular

(d) particle, perpendicular and circle

Answer: (a) particle, circle and perpendicular

**A particle performing uniform circular motion has angular momentum L. If its angular frequency is doubled and its kinetic energy halved, then the new angular momentum is**

(a) L/2

(b) L/4

(c) 2 L

(d) 4 L

Answer: (b) L/4

**A solid cylinder of mass 20 kg, has length 1 metre and radius 0.5m. then its momentum of inertia in kg m² about its geometrical axis is**

(a) 2.5

(b) 5

(c) 1.5

(d) 3

Answer: (a) 2.5

**Which is the wrong relation from the following?**

(a) t = I a

(b) F = ma

(c) L = I w

(d) I = t a

Answer: (d) I = t a

**A dancer on ice spins faster when she folds here arms. This is due to**

(a) Increases in energy and increase in angular momentum

(b) Decrease in friction at the skates

(c) Constant angular momentum and increase in kinetic energy

(d) Increase in energy an decreases in angular momentum

Answer: (c) Constant angular momentum and increase in kinetic energy

**The moment of inertia of a uniform semicircular disc of mass M and radius about a line perpendicular to the plane of the disc through the centre is**

(a) (2/5) Mr²

(b) (1/4) Mr power 2

(c) (1/2) Mr²

(d) Mr²

Answer: (c) (1/2) Mr²

**A body of M.I. 3 kg m² rotating with an angular velocity 2 rad/s has the same K.E. as a mass of 12 kg moving with a velocity of**

(a) 1 m/s

(b) 2 m/s

(c) 4 m/s

(d) 8 m/s

Answer: (a) 1 m/s

**Concrete mixture is made by mixing cement, stone and sand in a rotating cylindrical drum. If the drum rotates too fast, the ingredients remain stuck to the wall of the drum and proper mixing of ingredients does not take place. The maximum rotational speed of the drum in revolutions per minute (rpm) to ensure proper mixing is close to : (Take the radius of the drum to be 1.25 m and its axle to be horizontal):**

(a) 27.0

(b) 0.4

(c) 1.3

(d) 8.0

Answer: (a) 27.0

**If the resultant of all external forces is zero, then velocity of centre of mass will be**

(a) zero

(b) neither (a) nor (b)

(c) constant

(d) either (a) or (b)

Answer: (a) zero

**A stick is thrown in the air and lands on the ground at some distance from the thrower. The centre of mass of the stick will move along a parabolic path**

(a) in all cases

(b) only if the stick is uniform

(c) only if the stick has linear motion but no rotational motion

(d) only if the stick has a shape such that its centre of mass is located at some point on it and not outside it

Answer: (a) in all cases

**Assertion : The centre of mass of an isolated system has a constant velocity.Reason : If centre of mass of an isolated system is already at rest, it remains at rest.**

(a) Assertion is correct, reason is correct; reason is not a correct explanation for assertion

(b) Assertion is correct, reason is correct; reason is a correct explanation for assertion.

(c) Assertion is incorrect, reason is correct

(d) Assertion is correct, reason is incorrect

Answer: (a) Assertion is correct, reason is correct; reason is not a correct explanation for assertion

**If a body is rotating about an axis, passing through its centre of mass then its angular momentum is directed along its**

(a) Radius

(b) Tangent

(c) Circumference

(d) Axis of rotation

Answer: (d) Axis of rotation

**A particle moves on a circular path with decreasing speed. Choose the correct statement**

(a) Angular momentum remains constant

(b) Acceleration is towards the centre

(c) Particle moves on a spiral path with decreasing radius

(d) The direction of angular momentum remains constant

Answer: (d) The direction of angular momentum remains constant

**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) Moment of inertia

(b) Angular momentum

(c) Angular velocity

(d) Rotational kinetic energy

Answer: (b) Angular momentum

**A hollow cylinder and a solid cylinder having different mass diameter are released from rest simultaneously from the of an inclined plane. Which will reach the bottom first?**

(a) solid cylinder

(b) cant be determined without knowing their masses

(c) hollow cylinder

(d) cant be determined without knowing their diameters

Answer: (a) solid cylinder

**For increasing the angular velocity of an object by 10%, the kinetic energy has to be increased by**

(a) 40%

(b) 20%

(c) 10%

(d) 21%

Answer: (d) 21%

**Angular velocity of each particle of a rotating rigid body about axis of rotation is**

(a) same

(b) different

(c) depends on relative position

(d) None of these

Answer: (a) same

**A wheel has a speed of 1200 revolutions per minute and is made to slow down at a rate of 4 radians/s2. The number of revolutions it makes before coming to rest is**

(a) 314

(b) 722

(c) 272

(d) 143

Answer: (a) 314

**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) closer to the earth

**A thin uniform, circular ring is rolling down an inclined plane of inclination 300 without slipping. Its linear acceleration along the inclined plane will be**

(a) g/2

(b) g/3

(c) g/4

(d) 2g/3

Answer: (a) g/2

**A wheel rotates with a constant acceleration of 2.0 radian/sec2. If the wheel starts from rest, the number of revolutions it makes in the first ten seconds will be approximately**

(a) 16

(b) 24

(c) 32

(d) 8

Answer: (a) 16

**A particle moves for 20 s with velocity 3 m/s and then moves with velocity 4 m/s for another 20 s and finally moves with velocity 5 m/s for next 20 s. what is the average velocity of the particle?**

(a) 3 m/s

(b) 4 m/s

(c) 5 m/s

(d) Zero

Answer: (b) 4 m/s

**The position of centre of mass of a system of particles does not depend upon the**

(a) relative distance between the particles

(b) position of the particles

(c) symmetry of the body

(d) mass of particles

Answer: (a) relative distance between the particles

**Moment of inertia depends on**

(a) Distribution of particles

(b) Mass

(c) Position of axis of rotation

(d) All of these

Answer: (d) All of these

**If I, a and t are the moment of inertia, angular acceleration and torque respectively of a body rotating about any axis with angular velocity w, then**

(a) t = Ia

(b) t = Iw

(c) I = tw

(d) a = Iw

Answer: (a) t = Ia

**In rotatory motion, linear velocities of all the particles of the body are**

(a) different

(b) zero

(c) cannot say

(d) None of these

Answer: (a) different

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