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Tamil Nadu Board 11th Standard Physics - Unit 3: Book Back Answers and Solutions

This post covers the book back answers and solutions for Unit 3 – 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 3 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 3:Laws Of Motion

I. Multiple Choice Questions

1. When a car takes a sudden left turn in the curved road, passengers are pushed towards the right due to
(a) inertia of direction
(b) inertia of motion
(c) inertia of rest
(d) absence of inertia
Answer Key:
(a) inertia of direction

2. An object of mass m held against a vertical wall by applying horizontal force F as shown in the figure. The minimum value of the force F is (IIT JEE 1994)

(a) Less than mg

(b) Equal to mg

(d) Cannot determine

Answer Key:

3. A vehicle is moving along the positive x direction, if sudden brake is applied, then
(a) frictional force acting on the vehicle is along negative x direction
(b) frictional force acting on the vehicle is along positive x direction
(c) no frictional force acts on the vehicle
(d) frictional force acts in downward direction.
Answer Key:
(a) frictional force acting on the vehicle is along negative x direction

4. A book is at rest on the table which exerts a normal force on the book. If this force is considered as reaction force, what is the action force according to Newton’s third law?
(a) Gravitational force exerted by Earth on the book
(b) Gravitational force exerted by the book on Earth
(c) Normal force exerted by the book on the table
(d) None of the above
Answer Key:
(c) Normal force exerted by the book on the table

5. Two masses m₁ and m₂ are experiencing the same force where m₁< m₂. The ratio of their acceleration $\frac{a_{1}}{b_{1}}$

(a) 1
(b) less than 1
(c) greater than 1
(d) all the three cases

Answer Key:

6. Choose appropriate free body diagram for the particle experiencing net acceleration along negative y direction. (Each arrow mark represents the force acting on the system).

Answer Key:

7. A particle of mass m sliding on the smooth double inclined plane (shown in figure) will experience

(a) greater acceleration along the path AB

(b) greater acceleration along the path AC

(d) no acceleration in both the paths.

Answer Key:

(b) greater acceleration along the path AC

8. Two blocks of masses m and 2m are placed on a smooth horizontal surface as shown. In the first case only a force F₁ is applied from the left. Later only a force F₂ is applied from the right. If the force acting at the interface of the two m blocks in the two cases is same, then F ₁: F₂ is (Physics Olympiad 2016)

(a) 1:1
(b) 1:2
(c) 2:1
(d) 1:3
Answer Key:
(c) 2:1

9. Force acting on the particle moving with constant speed is
(a) always zero
(b) need not be zero
(c) always non zero
(d) cannot be concluded
Answer Key:
(b) need not be zero

10. An object of mass m begins to move on the plane inclined at an angle θ. The coefficient of static friction of inclined surface is $μ$ _s The maximum static friction experienced by the mass is

(a) mg

(b)

μ

_s mg

(c)

μ

_s mg sin θ

(d)

μ

_s mg cos θ

Answer Key:

(d)

μ

_s mg cos θ

11. When the object is moving at constant velocity on the rough surface,

(a) net force on the object is zero
(b) no force acts on the object
(c) only external force acts on the object
(d) only kinetic friction acts on the object
Answer Key:
(a) net force on the object is zero

12. When an object is at rest on the inclined rough surface,

(a) static and kinetic frictions acting on the object is zero
(b) static friction is zero but kinetic friction is not zero
(c) static friction is not zero and kinetic friction is zero
(d) static and kinetic frictions are not zero
Answer Key:
(c) static friction is not zero and kinetic friction is zero

13. The centrifugal force appears to exist
(a) only in inertial frames
(b) only in rotating frames
(c) in any accelerated frame
(d) both in inertial and non-inertial frames
Answer Key:

(b) only in rotating frames

14. Choose the correct statement from the following

(a) Centrifugal and centripetal forces are action reaction pairs
(b) Centripetal forces is a natural force
(c) Centrifugal force arises from gravitational force
(d) Centripetal force acts towards the centre and centrifugal force appears to act away from the centre in a circular motion
Answer Key:
(d) Centripetal force acts towards the centre and centrifugal force appears to act away from the centre in a circular motion

15. If a person moving from pole to equator, the centrifugal force acting on him

(a) increases
(b) decreases
(c) remains the same
(d) increases and then decreases
Answer Key:
(a) increases

II. Short Answer Questions

11th physics

III. Long Answer Questions

11th Physics

IV. Exercise

11th Physics