11th Physics - Book Back Answers - Unit 5 - English Medium Guides

 

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Tamil Nadu Board 11th Standard Physics - Unit 5: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 5 – Physics from the Tamil Nadu State Board 11th Standard Physics textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Physics Unit 5 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 11 students! Prepare well and aim for top scores. Thank you!

Unit 5:Motion Of System Of Particles And Rigid Bodies

I. Multiple Choice Questions

1. The centre of mass of a system of particles does not depend upon, [AIPMT 1997, AIEEE 2004]
(a) position of particles
(b) relative distance between particles
(c) masses of particles
(d) force acting on particle
Answer Key: 
(d) force acting on particle

2. A couple produces,      [AIPMT 1997]
(a) pure rotation
(b) pure translation
(c) rotation and translation
(d) no motion
Answer Key: 
(a) pure rotation

3. A particle is moving with a constant velocity along a line parallel to positive X-axis. The magnitude of its angular momentum with respect to the origin is,   [IIT 2002]
(a) zero
(b) increasing with x
(c) decreasing with x
(d) remaining constant
Answer Key: 
(d) remaining constant

4. 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 30 N? [NEET 2017]

(a) 0.25 rad s^–2

(b) 25 rad s^–2

(c) 5 m s^–2

(d) 25 m s^–2
Answer Key: 
(b) 25 rad s^–2

5. A closed cylindrical container is partially filled with water. As the container rotates in a horizontal plane about a perpendicular bisector, its moment of inertia,   [IIT 1998]
(a) increases 
(b) decreases
(c) remains constant
(d) depends on direction of rotation
Answer Key: 
(a) increases 

6. A rigid body rotates with an angular momentum L. If its kinetic energy is halved, the angular momentum becomes,    [AFMC 1998, AIPMT 2015]
(a) L 
(b) L/2
(c) 2L 
(d) L/ $\sqrt{2}$
Answer Key: 
(d) L/ 2

7. A particle undergoes uniform circular motion. The angular momentum of the particle remain conserved about,   [IIT 2003]
(a) the centre point of the circle.
(b) the point on the circumference of the circle.
(c) any point inside the circle.
(d) any point outside the circle.
Answer Key: 
(a) the centre point of the circle.

8. When a mass is rotating in a plane about a fixed point, its angular momentum is directed along,     [AIPMT 2012]
(a) a line perpendicular to the plane of rotation
(b) the line making an angle of 45° to the plane of rotation
(c) the radius
(d) tangent to the path
Answer Key: 
(a) a line perpendicular to the plane of rotation

9. 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 in to contact face to face coinciding the axis of rotation. The expression for loss of energy during this process is,   [NEET 2017]
(a) $$\begin{gathered} \frac{1}{4}\mathrm{I}({\mathrm{\omega }}_1-{\mathrm{\omega }}_2{)}^2\text{ \\ } \end{gathered}$$
(b) $\mathrm{I}({\mathrm{\omega }}_1-{\mathrm{\omega }}_2{)}^2$
(c) $\frac{1}{8}\mathrm{I}({\mathrm{\omega }}_1-{\mathrm{\omega }}_2{)}^2$
(d) $\frac{1}{2}\mathrm{I}({\mathrm{\omega }}_1-{\mathrm{\omega }}_2{)}^2$
Answer Key: 
(a) $\frac{1}{4}\mathrm{I}({\mathrm{\omega }}_1-{\mathrm{\omega }}_2{)}^2$

10. A disc of moment of inertia I_a  is rotating in a horizontal plane about its symmetry axis with a constant angular speed ω. Another discinitially at rest of moment of inertia I_b  is dropped coaxially on to the rotating disc. Then, both the discs rotate with same constant angular speed. The loss of kinetic energy due to friction in this process is,        [AIPMT 2001]
(a) $\frac{1}{2}\frac{{{\mathrm{I}}_{\mathrm{b}}}^2}{({\mathrm{I}}_{\mathrm{a}}+{\mathrm{I}}_{\mathrm{b}})}{\mathrm{\omega }}^2$
(b) $\frac{{{\mathrm{I}}_{\mathrm{b}}}^2}{({\mathrm{I}}_{\mathrm{a}}+{\mathrm{I}}_{\mathrm{b}})}{\mathrm{\omega }}^2$
(c) $\frac{({\mathrm{I}}_{\mathrm{b}}-{\mathrm{I}}_{\mathrm{a}}{)}^2}{({\mathrm{I}}_{\mathrm{a}}+{\mathrm{I}}_{\mathrm{b}})}{\mathrm{\omega }}^2$
(d) $\frac{1}{2}\frac{{\mathrm{I}}_{\mathrm{a}}{\mathrm{I}}_{\mathrm{b}}}{({\mathrm{I}}_{\mathrm{a}}+{\mathrm{I}}_{\mathrm{b}})}{\mathrm{\omega }}^2$
 Answer Key: 
(d) $\frac{1}{2}\frac{{\mathrm{I}}_{\mathrm{a}}{\mathrm{I}}_{\mathrm{b}}}{({\mathrm{I}}_{\mathrm{a}}+{\mathrm{I}}_{\mathrm{b}})}{\mathrm{\omega }}^2$

11. The ratio of the acceleration 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,        [AIPMT 2014]
(a) 5:7
(b) 2:3 
(c) 2:5 
(d) 7:5
Answer Key: 
(a) 5:7

12. From a disc of radius R a mass M, a circular hole of diameter R, whose rim passes through the centre is cut. What is the moment of inertia of the remaining part of the disc about a perpendicular axis passing through it  [NEET 2016]

(a) 15MR²/32

(b) 13MR²/32

(c) 11MR²/32

(d) 9MR²/32

Answer Key: 
(b) 13MR²/32

13. The speed of a solid sphere after rolling down from rest without sliding on an inclined plane of vertical height h is,
(a) $\sqrt{\frac{4}{3}\mathrm{gh}}$
(b) $\sqrt{\frac{10}{7}\mathrm{gh}}$
(c) $\sqrt{2\mathrm{gh}}$
(d) $\sqrt{\frac{1}{2}\mathrm{gh}}$
Answer Key: 
(b) $\sqrt{\frac{10}{7}\mathrm{gh}}$

14. The speed of the centre of a wheel rolling on a horizontal surface is v₀. A point on the rim in level with the centre will be moving at a speed of speed of,  [PMT 1992, PMT 2003, IIT 2004]
(a) zero 
(b) v₀
(c) 2v₀
(d) 2v₀
Answer Key: 
(c) 2v₀

15. A round object of mass M and radius R rolls down without slipping along an inclined plane. The frictional force,  [PMT 2005]
(a) dissipates kinetic energy as heat.
(b) decreases the rotational motion.
(c) decreases the rotational and transnational motion
(d) converts transnational energy into rotational energy
Answer Key:
(d) converts transnational energy into rotational energy

II. Short Answer Questions

11th physics

III. Long Answer Questions

11th Physics

IV. Exercise

11th Physics