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Complete Syllabus Question Paper
Grade 11 : Physics - Rotational Motion (Set 3)— Questions & Detailed Solutions
Q1
Two point masses $m_1 = 2kg$ and $m_2 = 3kg$ are connected by a rigid, light rod of length $L = 10m$.
What is the distance of the center of mass of the system measured from the 2 kg mass?
(A)
4 m
(B)
6 m
(C)
5 m
(D)
3 m
Q2
A thin uniform rod has a total mass $M = 4kg$ and length $L = 3m$.Calculate its moment of inertia about an axis perpendicular to the rod and passing through one of its ends.
A thin uniform rod has a total mass $M = 4kg$ and length $L = 3m$.
Calculate its moment of inertia about an axis perpendicular to the rod and passing through one of its ends.
(A)
$36kg\cdotm^2$
(B)
$4kg\cdotm^2$
(C)
$12kg\cdotm^2$
(D)
$18kg\cdotm^2$
Q3
A solid sphere of mass $M = 5kg$ and radius $R = 2m$ is considered along with a line tangent to its outer surface.Using the parallel axis theorem, find the moment of inertia of the solid sphere about an axis tangent to its surface.
A solid sphere of mass $M = 5kg$ and radius $R = 2m$ is considered along with a line tangent to its outer surface.
Using the parallel axis theorem, find the moment of inertia of the solid sphere about an axis tangent to its surface.
(A)
$28kg\cdotm^2$
(B)
$20kg\cdotm^2$
(C)
$14kg\cdotm^2$
(D)
$8kg\cdotm^2$
Q4
A heavy flywheel starts rotating from rest under a constant angular acceleration $\alpha = 4\text{ rad/s}^2$.What is the magnitude of its angular velocity after $t = 5seconds$?
A heavy flywheel starts rotating from rest under a constant angular acceleration $\alpha = 4\text{ rad/s}^2$.
What is the magnitude of its angular velocity after $t = 5seconds$?
(A)
10 rad/s
(B)
40 rad/s
(C)
50 rad/s
(D)
20 rad/s
Q5
A particle of mass $m = 0.5kg$ moves along a straight line $y = 3m$ with a constant velocity of $v = 4m/s$ parallel to the x-axis.What is the magnitude of the angular momentum of the particle about the origin?
A particle of mass $m = 0.5kg$ moves along a straight line $y = 3m$ with a constant velocity of $v = 4m/s$ parallel to the x-axis.
What is the magnitude of the angular momentum of the particle about the origin?
(A)
$12kg\cdotm^2/\text{s}$
(B)
$6kg\cdotm^2/\text{s}$
(C)
$3kg\cdotm^2/\text{s}$
(D)
$2.5kg\cdotm^2/\text{s}$
Q6
A turntable of moment of inertia $I_1 = 400kg\cdotm^2$ rotates freely about a vertical axis at an angular speed $\omega_1 = 3\text{ rad/s}$. A child steps onto the outer rim, increasing the total moment of inertia to $I_2 = 600kg\cdotm^2$.Assuming no external torque acts on the system, what is the new angular velocity of the turntable?
A turntable of moment of inertia $I_1 = 400kg\cdotm^2$ rotates freely about a vertical axis at an angular speed $\omega_1 = 3\text{ rad/s}$. A child steps onto the outer rim, increasing the total moment of inertia to $I_2 = 600kg\cdotm^2$.
Assuming no external torque acts on the system, what is the new angular velocity of the turntable?
(A)
2 rad/s
(B)
4.5 rad/s
(C)
1.5 rad/s
(D)
3 rad/s
Q7
A net torque $\tau = 50\text{ N}\cdotm$ is applied to a rigid body having a moment of inertia $I = 10kg\cdotm^2$ about its rotation axis.Find the angular acceleration produced in the body.
A net torque $\tau = 50\text{ N}\cdotm$ is applied to a rigid body having a moment of inertia $I = 10kg\cdotm^2$ about its rotation axis.
Find the angular acceleration produced in the body.
(A)
$500\text{ rad/s}^2$
(B)
$0.2\text{ rad/s}^2$
(C)
$5\text{ rad/s}^2$
(D)
$25\text{ rad/s}^2$
Q8
A uniform solid disc has mass $M = 2kg$ and radius $R = 0.5m$. It rotates about an axis passing through its center perpendicular to its plane at $\omega = 10\text{ rad/s}$.Determine the rotational kinetic energy of the disc.
A uniform solid disc has mass $M = 2kg$ and radius $R = 0.5m$. It rotates about an axis passing through its center perpendicular to its plane at $\omega = 10\text{ rad/s}$.
Determine the rotational kinetic energy of the disc.
(A)
25 J
(B)
12.5 J
(C)
50 J
(D)
6.25 J
Q9
A solid cylinder rolls without slipping on a horizontal plane.What is the ratio of its rotational kinetic energy to its total kinetic energy?
A solid cylinder rolls without slipping on a horizontal plane.
What is the ratio of its rotational kinetic energy to its total kinetic energy?
(A)
$1/2$
(B)
$2/3$
(C)
$1/4$
(D)
$1/3$
Q10
Consider a thin uniform circular ring of radius $R = 6cm$.Calculate the radius of gyration of the ring about an axis lying along one of its diameters.
Consider a thin uniform circular ring of radius $R = 6cm$.
Calculate the radius of gyration of the ring about an axis lying along one of its diameters.
(A)
$3\sqrt{2}cm$
(B)
3 cm
(C)
6 cm
(D)
4.5 cm
Q11
Three particles of masses 1 kg, 2 kg, and 3 kg are located at the vertices $(0,0)$, $(2,0)$, and $(1, \sqrt{3})$ of an equilateral triangle in meters.Find the coordinates of the center of mass of this three-particle system.
Three particles of masses 1 kg, 2 kg, and 3 kg are located at the vertices $(0,0)$, $(2,0)$, and $(1, \sqrt{3})$ of an equilateral triangle in meters.
Find the coordinates of the center of mass of this three-particle system.
(A)
$(1, \sqrt{3}/3)$
(B)
$(7/6, \sqrt{3})$
(C)
$(7/6, \sqrt{3}/2)$
(D)
$(5/6, \sqrt{3}/2)$
Q12
A heavy wheel of moment of inertia $I = 4kg\cdotm^2$ is rotating at an initial angular speed $\omega_0 = 6\text{ rad/s}$. A friction brake exerts a torque to bring it completely to rest.What is the magnitude of work done by the retarding torque on the wheel?
A heavy wheel of moment of inertia $I = 4kg\cdotm^2$ is rotating at an initial angular speed $\omega_0 = 6\text{ rad/s}$. A friction brake exerts a torque to bring it completely to rest.
What is the magnitude of work done by the retarding torque on the wheel?
(A)
144 J
(B)
72 J
(C)
36 J
(D)
24 J
Q13
A uniform square plate has mass $M = 12kg$ and side length $a = 2m$.Using the perpendicular axis theorem, calculate its moment of inertia about an axis passing through its center and lying in its plane parallel to one of its sides.
A uniform square plate has mass $M = 12kg$ and side length $a = 2m$.
Using the perpendicular axis theorem, calculate its moment of inertia about an axis passing through its center and lying in its plane parallel to one of its sides.
(A)
$4kg\cdotm^2$
(B)
$8kg\cdotm^2$
(C)
$12kg\cdotm^2$
(D)
$2kg\cdotm^2$
Q14
A solid sphere of radius $R$ is allowed to roll down an inclined plane of inclination $\theta = 30^\circ$ without slipping. Acceleration due to gravity is $g = 9.8m/s^2$.Calculate the linear acceleration of the center of mass of the sphere.
A solid sphere of radius $R$ is allowed to roll down an inclined plane of inclination $\theta = 30^\circ$ without slipping. Acceleration due to gravity is $g = 9.8m/s^2$.
Calculate the linear acceleration of the center of mass of the sphere.
(A)
$4.9m/s^2$
(B)
$2.45m/s^2$
(C)
$7.0m/s^2$
(D)
$3.5m/s^2$
Q15
A uniform ladder of length 5 m and mass 20 kg rests against a smooth vertical wall with its lower end on a rough horizontal floor at a distance of 3 m from the wall. Assume $g = 10m/s^2$.What is the magnitude of the normal reaction force exerted by the wall on the upper end of the ladder?
A uniform ladder of length 5 m and mass 20 kg rests against a smooth vertical wall with its lower end on a rough horizontal floor at a distance of 3 m from the wall. Assume $g = 10m/s^2$.
What is the magnitude of the normal reaction force exerted by the wall on the upper end of the ladder?
(A)
100 N
(B)
150 N
(C)
75 N
(D)
200 N
Q16
A solid sphere is released from rest from the top of an inclined plane of vertical height $h = 7m$ and rolls down without slipping ($g = 10m/s^2$).What is the linear speed of its center of mass when it reaches the bottom of the incline?
A solid sphere is released from rest from the top of an inclined plane of vertical height $h = 7m$ and rolls down without slipping ($g = 10m/s^2$).
What is the linear speed of its center of mass when it reaches the bottom of the incline?
(A)
11.8 m/s
(B)
10 m/s
(C)
8.36 m/s
(D)
14 m/s
Q17
A constant torque of magnitude $\tau = 20\text{ N}\cdotm$ acts on a rotating flywheel for a time interval of $t = 3seconds$.Calculate the magnitude of change in angular momentum of the flywheel.
A constant torque of magnitude $\tau = 20\text{ N}\cdotm$ acts on a rotating flywheel for a time interval of $t = 3seconds$.
Calculate the magnitude of change in angular momentum of the flywheel.
(A)
$60kg\cdotm^2/\text{s}$
(B)
$20kg\cdotm^2/\text{s}$
(C)
$6.67kg\cdotm^2/\text{s}$
(D)
$120kg\cdotm^2/\text{s}$
Q18
A uniform rod of mass $M = 6kg$ and length $L = 2m$ is tilted so that an axis passes through its center of mass making an angle of $\theta = 60^\circ$ with its length.Find the moment of inertia of the rod about this axis.
A uniform rod of mass $M = 6kg$ and length $L = 2m$ is tilted so that an axis passes through its center of mass making an angle of $\theta = 60^\circ$ with its length.
Find the moment of inertia of the rod about this axis.
(A)
$2.0kg\cdotm^2$
(B)
$0.75kg\cdotm^2$
(C)
$1.5kg\cdotm^2$
(D)
$3.0kg\cdotm^2$
Q19
A circular disc of moment of inertia $I_1 = 2kg\cdotm^2$ rotates horizontally about a vertical axis at $\omega_1 = 10\text{ rad/s}$. Another non-rotating disc of moment of inertia $I_2 = 3kg\cdotm^2$ is dropped concentrically onto it.Calculate the total loss in kinetic energy due to friction between the two discs.
A circular disc of moment of inertia $I_1 = 2kg\cdotm^2$ rotates horizontally about a vertical axis at $\omega_1 = 10\text{ rad/s}$. Another non-rotating disc of moment of inertia $I_2 = 3kg\cdotm^2$ is dropped concentrically onto it.
Calculate the total loss in kinetic energy due to friction between the two discs.
(A)
40 J
(B)
100 J
(C)
20 J
(D)
60 J
Q20
A wheel of radius $R = 0.4m$ rolls without slipping on a horizontal ground surface.If the linear speed of the top-most point of the wheel relative to the ground is 12 m/s, what is the linear speed of its center of mass?
A wheel of radius $R = 0.4m$ rolls without slipping on a horizontal ground surface.
If the linear speed of the top-most point of the wheel relative to the ground is 12 m/s, what is the linear speed of its center of mass?
(A)
12 m/s
(B)
6 m/s
(C)
3 m/s
(D)
24 m/s

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