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NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11 PDF Download

2024

Q1: The moment of inertia of a thin rod about an axis passing through its mid point and perpendicular to the rod is  2400gcm2. The length of the 400g rod is nearly: [2024]
(a) 8.5 cm
(b) 17.5 cm
(c) 20.7 cm
(d) 72.0 cm
Ans:
(a) 8.5 cm

Explanation:

Moment of Inertia of rod = NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Q2: A wheel of a bullock cart is rolling on a level road as shown in the figure below. If its linear speed is v in the direction shown, which one of the following options is correct (P and Q are any highest and lowest points on the wheel, respectively)?     [2024]
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11(a) Point P moves slower than point Q
(b) Point P moves faster than point Q
(c) Both the points P and Q move with equal speed
(d) Point P has zero speed
Ans: 
(b) Point P moves faster than point Q

Explanation:

In the case of pure rolling,NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11 The linear speed of the centre of the wheel is v. Points P and 
Q
Q are the highest and lowest points on the wheel, respectively.

For rolling motion, every point on the wheel has two components of velocity:

  1. The translational velocity due to the movement of the entire wheel (v).
  2. The rotational velocity due to the wheel spinning. The velocity of a point on the rim is
    ωR (where 
    ω is the angular velocity, and 
    R
    R is the radius of the wheel).
  •  For the topmost point (P)
    (i) The translational velocity is v (forward direction).
    (ii) The rotational velocity at P is 
    v (forward direction, since it rotates along with the wheel).
    (iii) So, the total velocity of P is v+v=2v+v = 2v (forward).
  • For the bottommost point (Q):
    (i) The translational velocity is 
    v (forward).
    (ii) The rotational velocity at Q is 
    v (backward direction, because it rotates in the opposite direction of translational motion).
    (iii) So, the total velocity at Q is 
    v−v=0.


2023

Q1: The ratio of radius of gyration of a solid sphere of mass M and radius R about its own axis to the radius of gyration of the thin hollow sphere of same mass and radius about its axis is       [2023]
(a) 3 : 5 
(b) 5 : 3
(c) 2 : 5
(d) 5 : 2
Ans:
(a) 3 : 5

Explanation:

The moment of inertia II of a body about a given axis is related to the radius of gyration KK by the equation: NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Where:

  • II= Moment of inertia
  • MM = Mass of the body
  • KK = Radius of gyration

For a solid sphere rotating about its own axis, the moment of inertia is given by:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

For a thin hollow sphere rotating about its own axis, the moment of inertia is given by:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Now, we take the ratio of the radius of gyration of the solid sphere to the hollow sphere:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11


Q2: The angular acceleration of a body, moving along the circumference of a circle, is :
(a) along the radius towards the centre
(b) along the tangent to its position
(c) along the axis of rotation
(d) along the radius, away from centre                       [2023]
Ans:
(c) along the axis of rotation

Explanation:

Angular acceleration refers to the rate of change of angular velocity of a body moving in a circular path. Angular acceleration is a vector quantity, and its direction depends on the direction of the change in angular velocity.

  • When a body moves along the circumference of a circle, its angular acceleration is associated with the axis of rotation, which is perpendicular to the plane of motion.

  • The direction of angular acceleration is the same as the direction of the change in angular velocity. For rotational motion, the axis of rotation determines the orientation of angular velocity and angular acceleration.

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

2022

Q1: An energy of 484 J is spent in increasing the speed of a flywheel from 60 rpm to 360 rpm. The moment of inertia of the flywheel is 
(a) 0.07 kg-m2
(b) 0.7 kg-m2
(c) 3.22 kg-m2
(c) 30.8 kg-m2
Ans: 
(b) 0.7 kg-m2

Explanation:
Given:

Energy spent E=484 JE = 484 \, \text{J J

Initial angular speed  ω= 60 rpm

Final angular speed ω2 = 360rpm

1. Convert the angular speeds to radians per second (rad/s):

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

2. The change in rotational kinetic energy is given by:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

3. Substitute the known values into the equation:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Q2: The angular speed of a fly wheel moving with uniform angular acceleration changes from 1200 rpm to 3120 rpm in 16 seconds. The angular acceleration in rad/s2 is [2022]
(a) 2π
(b) 4π
(c) 12π
(d) 104π
Ans: 
(b) 4π

Explanation:

Given:

Initial angular speed, ω1=1200 rpm

Final angular speed, ω2=3120 rpm

Time interval, t=16 seconds

Convert angular speeds to radians per second (rad/s):

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Angular acceleration α is given by the formula:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11


Q3: Two objects of mass 10 kg and 20 kg respectively are connected to the two ends of a rigid rod of length 10 m with negligible mass. The distance of the center of mass of the system from the 10 kg mass is              [2022]
(a) 20/3 m 
(b) 10 m 
(c) 5 m 
(d) 10/3 m
Ans: (a) 20/3 m

Explanation:
Given:

Mass of the first object, m1=10 kg

Mass of the second object, m2=20 kgm_2 = 20 \, \text{kg} kg

Length of the rod, L=10 mL = 10 \, \text{m} m

We need to find the distance of the center of mass from the 10 kg mass.

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11 

Q4: The ratio of the radius of gyration of a thin uniform disc about an axis passing through its center and normal to its plane to the radius of gyration of the disc about its diameter is       [2022]
(a) √2: 1
(b) 4: 1
(c) 1: √2
(d) 2: 1  

Ans: (a) √2: 1

Explanation:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Now, we take the ratio of the radius of gyration about the center to that about the diameter:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

2021

Q1: From a circular ring of mass 'M' and radius 'R' an arc corresponding to a 90° sector is removed. The moment of inertia of the remaining part of the ring about an axis passing through the centre of the ring and perpendicular to the plane of the ring is 'K' times 'MR2'. Then the value of 'K' is :     [2021]
(a) 1/4
(b) 1/8

(c) 3/4
(d) 7/8
Ans: (c) 
3/4

Explanation:

The moment of inertia of a full circular ring about its center and perpendicular to the plane is:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Since a 90° sector is removed, this represents 14\frac{1}{4} of the total mass of the ring. The mass of the removed sector is: NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

The moment of inertia of the removed sector is proportional to its mass, so:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Now, NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

The moment of inertia of the remaining part is given as
K \times M R^2
K×MR2, so:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11


Q2: A uniform rod of length 200 cm and mass 500 g is balanced on a wedge placed at 40 cm mark. A mass of 2 kg is suspended from the rod at 20 cm and another unknown mass 'm' is suspended from the rod at 160 cm mark as shown in the figure. Find the value of 'm' such that the rod is in equilibrium. (g=10 m/s2)    [2021]
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
(a) 1/6 kg
(b) 1/12 kg
(c) 1/2 kg
(d) 1/3 kg
Ans: 
(b) 1/12 Kg

Explanation:

Given:
Length of the rod = 200 cm

Mass of the rod = 500 g = 0.5 kg

The rod is balanced at the 40 cm mark.

A mass of 2 kg is suspended at the 20 cm mark.

An unknown mass mmm is suspended at the 160 cm mark.

The rod is in equilibrium, and the acceleration due to gravity g= 10m/s2.

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Torque due to the 2 kg mass at 20 cm:

The distance from the pivot (40 cm) to the 2 kg mass (at 20 cm) is: 

d1=4020=20cm = 0.2m

Torque due to this mass (T1) is:

T1=2×g×0.2=2×10×0.2=44Nm

This torque is clockwise.

Torque due to the unknown mass
m
m at 160 cm:

The distance from the pivot (40 cm) to the unknown mass
m
m (at 160 cm) is:

d2=16040=120 cm = 1.2m

Torque due to this mass (T_2T2) is:

T2=m×g×1.2=m×10×1.2=12 m Nm

This torque is counterclockwise.

Torque due to the mass of the rod:

The rod's mass acts at its center of mass, which is at the midpoint of the rod (100 cm).

The distance from the pivot (40 cm) to the center of mass (100 cm) is:

d3=10040=60 cm=0.6 m

Torque due to the rod's mass (T3) is:

T= 0.5 × g × 0.6 = 0.5×10×0.6=3Nm

This torque is counterclockwise.

Equilibrium Condition (Net Torque = 0):The sum of clockwise and counterclockwise torques must balance:

T1= T2 + T3

Substituting the values:

4=12m+34 = 12m + 3

Solving for
m
m:

4 - 3 = 12m4−3=12m

or  1=12m

orNEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

2020

Q1: Find the torque about the origin when a force ofNEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11acts on a particle whose position vector is NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11 [2020]
(a) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
(b) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11 

(c) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
(d) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Ans: (a) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Explanation:
Given:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Q2: Two particles of mass 5kg and 10 kg respectively are attached to the two ends of a rigid rod of length 1m with negligible mass. The centre of mass of the system from the 5kg particle is nearly at a distance of: [2020]
(a) 67 cm
(b) 80 cm
(c) 33 cm
(d) 50 cm
Ans:
(a) 67 cm

Explanation:
Given:

Mass of the first particle, m1=5kg

Mass of the second particle, m2=10kg

Length of the rod, L=1m =100cm

We need to find the distance of the center of mass from the 5 kg particle.

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

2019

Q1: A solid cylinder of mass 2 kg and radius 4 cm is rotating about its axis at the rate of 3 rpm. The torque required to stop after 2π revolutions is    [2019]
(a) 2 × 10-6 N m
(b) 2 × 10-3 N m
(c) 12 × 10-4 N m
(d) 2 × 106 N m
Ans:
(a)  2 × 10-6 N m

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

We take only magnitude, therefore, NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Q2: Two particles A and B are moving in uniform circular motion in concentric circles of radii rA and rB with speed vA and vB respectively. Their time period of rotation is the same. The ratio of angular speed of A to that of B will be: [2019]
(a) rA : rB
(b) vA : vB
(c) rB : rA
(d) 1 : 1
Ans:
(d) 1 : 1

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Q3: A disc of radius 2 m and mass 100 kg rolls on a horizontal floor. Its centre of mass has speed of 20 cm/s. How much work is needed to stop it?               [2019]
(a) 1 J
(b) 2 J
(c) 3 J
(d) 30 J
Ans:
(c) 3 J

Explanation:
Given:

Radius of the disc, R=2 m

Mass of the disc, M=100 kg

Speed of the center of mass, vcm=20 cm/s = 0.2m/s

We need to find the work required to stop the disc.

When the disc is rolling on a horizontal surface, it has both translational kinetic energy and rotational kinetic energy.

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

For a solid disc, the moment of inertia about its axis is:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

2018

Q1: Three objects, A : (a solid sphere), B : (a thin circular disk) and C = (a circular ring), each have the same mass M and radius R. They all spin with the same angular speed ω about their own symmetry axes. The amounts of work (W) required to bring them to rest, would satisfy the relation:-    [2018]
(a) WC > WB > WA
(b) WA > WB > WC
(c) WB > WA > WC
(d) WB > WA > W
C
Ans: (a) WC > WB > WA

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Q2: The moment of the force, NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11 at (2, 0, –3), about the point (2, –2, –2), is given by:- [2018]
(a) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
(b) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
(c) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
(d) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
Ans:
(d) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Q3: A solid sphere is in rolling motion. In rolling motion a body possesses translational kinetic energy (Kt) as well as rotational kinetic energy (Kr) simultaneously. The ratio Kt : (Kt + Kr) for the sphere is    [2018]
(a) 7 : 10
(b) 5 : 7
(c) 10 : 7
(d) 2 : 5
Ans: (b)  5 : 7

Explanation:
Given: 

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11


Q4: A solid sphere is rotating freely about its symmetry axis in free space. The radius of the sphere is increased keeping its mass same. Which of the following physical quantities would remain constant for the sphere ?    [2018]
(a) Angular velocity
(b) Moment of inertia
(c) Rotational kinetic energy
(d) Angular momentum
Ans: (d) Angular Momentum

Explanation:
(a) Angular momentum (L): 
In free space, no external torque acts on the sphere, so angular momentum remains conserved (as per the law of conservation of angular momentum). Angular momentum is given by:

L=IωL = I \omega

Where:

I is the moment of inertia.

ω is the angular velocity.

Since no external torque is acting, angular momentum remains constant.

(b) Moment of inertia (I): The moment of inertia of a solid sphere about its axis is given by:

I=25MR2I = \frac{2}{5} M R^2

Where:

M is the mass of the sphere.

R is the radius of the sphere.

As the radius R increases, the moment of inertia will increase.

(c) Angular velocity (ω): From the equation L= Iω, if the moment of inertia

(d) Rotational kinetic energy (K):The rotational kinetic energy is given by:

K=12 Iω2K = \frac{1}{2} I \omega^2

As I increases and 
\omega
ω decreases, the rotational kinetic energy will change (decrease) because both
I
I and
\omega
ω are changing in opposite directions.

I

2017

Q1: A rope is wound around a hollow cylinder of mass 3 kg and radius 40 cm. What is the angular acceleration of the cylinder if the rope is pulled with a force of 30 N ?    [2017]
(a) 0.25 rad/s2
(b) 25 rad/s2
(c) 5 m/s2
(d) 25 m/s2
Ans:
(b) 25 rad/s2

Explanation:

Given:

Mass of the hollow cylinder,
 kgM = 3 \, \text{kg}
M =3 kg

Radius of the cylinder,  mR = 40 \, \text{cm} = 0.4 \, \text{m}R = 40 cm = 0.4 m

Force applied on the rope, F = 30 N

We need to find the angular acceleration α of the cylinder.NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

The moment of inertia I of a hollow cylinder about its axis is:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

The angular acceleration is related to torque and moment of inertia by the equation:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

\alpha


Q2: Two discs of same moment of inertia rotating about their regular axis passing through centre and perpendicular to the plane of disc with angular velocities ω1 and ω2. They are brought into contact face to face coinciding the axis of rotation. The expression for loss of energy during this process is:- [2017]
(a) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
(b)NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
(c) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
(d) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
Ans: (a) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Explanation:
The initial kinetic energy of the system (both discs) before being brought into contact is:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

When the two discs are brought into contact and rotate together, the total angular momentum is conserved. Therefore:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

After the discs are brought into contact, the final kinetic energy of the system is:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

The energy lost during the process is the difference between the initial and final kinetic energies:

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11


Q3: Which of the following statements are correct ?    [2017]
(a) Centre of mass of a body always coincides with the centre of gravity of the body
(b) Central 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 produces 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) (a) and (b)
(b) (b) and (c)
(c) (c) and (d)
(d) (b) and (d)
Ans:
(d) (b) and (d)

Explanation:
(
a) Centre of mass of a body always coincides with the centre of gravity of the body:

False: The center of mass and the center of gravity coincide only in a uniform gravitational field. In non-uniform fields, they may not coincide because the center of gravity depends on the distribution of gravitational forces.

(b) Centre of mass of a body is the point at which the total gravitational torque on the body is zero:

True: The center of mass is the point where all the mass of the body can be considered to be concentrated, and the total gravitational torque about this point is zero.

(c) A couple on a body produces both translational and rotational motion in a body:

False: A couple consists of two equal and opposite forces whose lines of action do not coincide. A couple produces only rotational motion without any translational motion, as the net force is zero but the net torque is not.

(d) Mechanical advantage greater than one means that small effort can be used to lift a large load:

True: Mechanical advantage (MA) is the ratio of load to effort. When MA is greater than 1, a small effort is sufficient to lift a large load, making it easier to perform the task.

Conclusion:

(b) is true because the center of mass is the point where the total gravitational torque is zero.

(d) is true because mechanical advantage greater than 1 means a small effort can lift a large load.

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

2016

Q1: From a disc of radius R and mass M1 a circular hole of diameter R1 whose rim passes through the centre is cut. What is the moment of inertia of the remaining part of the disc about at perpendicular axis, passing through the centre ? [2016]
(a) 9MR2/32
(b) 15MR2/32
(c) 13MR2/32
(d) 11 MR2/32
Ans
: (c) 3MR2/32

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
Option C is correct Answer.

Q2: 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 ?    [2016]
(a) Depends on their masses
(b) Disk
(c) Sphere
(d) both reach at the same time
Ans:
(c) Sphere

Explanation:
When a disk and a sphere roll down an inclined plane, the speed at which they reach the bottom depends on the distribution of mass in relation to their rotation. This is determined by their moment of inertia and how it affects their total kinetic energy.

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Q3: 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 2.0 s is approximately : [2016]
(a) 3.0
(b) 8.0
(c) 7.0
(d) 6.0
Ans:
(b) 8.0

Explanation:
The angular speed of disc increases with time, and hence centripetal acceleration also increases.

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Q4: A light rod of length l has two masses mand m2 attached to its two ends. The moment of inertia of the system about an axis perpendicular to the rod and passing through the centre of mass is [2016]
(a) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

(b) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

(c) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

(d) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Ans: (a) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Q5: A solid sphere of mass m and radius R is rotating about its diameter. A solid cylinder of same mass and same radius is also rotating about its geometrical axis with an angular speed twice that of the sphere. The ratio of their kinetic energies of rotation (Esphere / Ecylinder) will be [2016]
(a) 2 : 3
(b) 1 : 5
(c) 1 : 4
(d) 3 : 1
Ans:
(b) 1 : 5

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

2015

Q1: Three identical spherical shells, each of mass m and radius r are placed as shown in figure. Consider an axis XX' which is touching to two shells and passing through diameter of third shell. Moment of inertia of the system consisting of these three spherical shells about XX' axis is :    [2015]
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
(a) 4 mr2
(b) 11/5 mr2
(c) 3 mr2
(d) 16/5 mr2
Ans:
(a) 4 mr2

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
Similarly the moment of inertia of the spherical shell C about the XX' axis is
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11


Q2: A rod of weight W is supported by two parallel knife edges A and B and is in equilibrium in a horizontal position. The knives are at a distance d from each other. The centre of mass of the rod is at distance x from A. The normal reaction on A is [2015]
(a) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

(b) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

(c) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

(d) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11
Ans:
(b) NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11Given situation is shown in figure.
N1 = Normal reaction on A
N= Normal reaction on B
W = Weight of the rod
In vertical equilibrium,
N1 + N= W …(i)
Torque balance about centre of mass of the rod,
N1x = N2(d – x)
Putting value of N2 from equation (i)
N1x = (W – N1)(d – x)
 N1x = Wd – Wx – N1d + N1x
 N1d = W(d – x) 

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11


Q3: Three identical spherical shells, each of mass m and radius r are placed as shown in figure. Consider an axis XX' which is touching to two shells and passing through diameter of third shell. Moment of inertia of the system consisting of these three spherical shells about XX' axis is      [2015]

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

(a) 16/5mr2
(b) 4mr2
(c) 11/5mr2
(d) 3mr2
Ans:
(b) 4mr2

Explanation:
Net moment of inertia of the system,
I = I1 + I2 + I3
The moment of inertia of a shell about its diameter, 

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11


Q4: An automobile moves on a road with a speed of 54 km h1. 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 15 s, the magnitude of average torque transmitted by its brakes to the wheel is
(a) 10.86 kg m2 s2
(b) 2.86 kg m2 s2
(c) 6.66 kg m2 s2
(d) 8.58 kg m2 s2
Ans:
(c) 6.66 kg m2 s2

Explanation:
Here, Speed of the automobile,

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

Radius of the wheel of the automobile, R = 0.45 m
Moment of inertia of the wheel about its axis of rotation, I = 3 kg m2
Time in which the vehicle brought to rest, t = 15 s
The initial angular speed of the wheel is 

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11


Q5: A force NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11 is acting at a point NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11. The value of αfor which angular momentum about origin is conserved is [2015]
(a) Zero
(b) 1
(c) -1
(d) 2
Ans:
(c) -1

Explanation:
From Newton's second law for rotational motion,

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

2014

Q1: 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: [2014]
(a) 78.5 N
(b) 157 N
(c) 25 πN
(d) 50 N
Ans:
(b) 157 N

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11


Q2: The ratio of the accelerations for a solid sphere (mass ‘m’ and radius ‘R’) rolling down an incline of angle ‘θ’ without slipping and slipping down the incline without rolling is :    [2014]
(a) 2 : 5
(b) 7 : 5
(c) 5 : 7
(d) 2 :3
Ans:
(c) 5 :7

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11



Q3: A body of mass (4m) is lying in x−y plane at rest. It suddenly explodes into three pieces. Two pieces, each of mass (m) move perpendicular to each other with equal speeds (ν). The total kinetic energy generated due to explosion is :    [2014]
(a) 2 mν2
(b) 4 mν2
(c) mν2
(d) 3/2 mν2
Ans: 
(d) 3/2 mv2

Explanation:
NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11

The document NEET Previous year questions (2014-2024): System of Particles & Rotational Motion | Physics Class 11 is a part of the NEET Course Physics Class 11.
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FAQs on NEET Previous year questions (2014-2024): System of Particles & Rotational Motion - Physics Class 11

1. What are the key concepts of System of Particles in NEET Physics?
Ans. The key concepts of System of Particles include the center of mass, motion of the center of mass, system of forces, and the conditions of equilibrium. Understanding how forces act on a system of particles and how they affect the motion of the entire system is crucial for solving problems in this topic.
2. How do I calculate the center of mass for a system of particles?
Ans. To calculate the center of mass for a system of particles, you can use the formula: \[ R_{cm} = \frac{\sum m_i \cdot r_i}{\sum m_i} \] where \( m_i \) is the mass of each particle and \( r_i \) is the position vector of each particle. The center of mass coordinates can be found separately for each dimension (x, y, z).
3. What is the importance of rotational motion in NEET exams?
Ans. Rotational motion is important in NEET exams as it covers concepts like angular velocity, angular acceleration, torque, moment of inertia, and conservation of angular momentum. Understanding these concepts is essential for solving problems related to rotating systems and helps in grasping the fundamentals of mechanics.
4. How do I solve problems related to torque and moment of inertia?
Ans. To solve problems related to torque and moment of inertia, start by identifying the axis of rotation and the forces acting on the object. Use the formula for torque \( \tau = r \times F \) and for moment of inertia \( I = \sum m_i r_i^2 \). Apply Newton's second law for rotation \( \tau = I \alpha \) to relate torque to angular acceleration.
5. What are some common types of questions asked in NEET regarding System of Particles and Rotational Motion?
Ans. Common types of questions include calculating the center of mass of a system, determining torque on an object, finding the moment of inertia for different shapes, and problems involving the equilibrium of rotational systems. Students may also encounter conceptual questions that test their understanding of the relationships between linear and angular quantities.
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