NCERT Solutions For Class 11 Physics Chapter 3: Motion in a Straight Line

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NCERT Solutions for Class 11 Physics Chapter 3 Motion in a Straight Line deals with the concepts of Position, path length and displacement, acceleration, kinematic equations, and relative velocity. Motion is the change in the position of an object over a specific period of time with respect to its surroundings. According to Newton’s first law of motion, a body without any net force on it continues to move in a straight line with a permanent velocity until and unless the body is subjected to a net force.

Class 11 Physics Chapter 3 Motion in a Straight Line belongs to Unit 2 Kinematics. Unit 2 along with Unit 1 Physical World and Measurement and Unit 3 Laws of Motion has a weightage of 23 marks. Class 11 Physics Chapter 3 NCERT Solutions covers position-time graphs, calculation of velocity, acceleration, etc.

Download PDF: NCERT Solutions for Class 11 Physics Chapter 3

NCERT Solutions for Class 11 Physics Chapter 3

Read More: Motion in a Straight Line MCQ

Class 11 Physics Chapter 3 – Concepts Covered

An object is in motion if its position changes with time

Based on the position coordinates, motion can be classified as –

(i) One-dimensional motion: A particle in motion along a straight line or a path is said to be in one dimensional motion.
(ii) Two-dimensional motion: A particle in motion in a plane is said to be in two dimensional motion.
(iii) Three-dimensional motion: A particle that is moving in space is said to undergo three dimensional motion.

The total length of the actual path travelled by a particle between its initial and final positions is referred to as the distance travelled by the particle.
Displacement of a particle is the change in the position of a particle in a particular direction during a period of time.

- Displacement has direction while distance does not.

- The magnitude of displacement can be both negative and positive whereas distance is always positive.

Speed is the time rate at which a given object is moving along a path.

An object is said to move with a uniform speed if it covers equal distances in equal intervals of time, howsoever small these intervals may be.

Velocity is the rate and direction of the movement of an object.

An object is said to move with uniform velocity if it covers equal displacements in equal intervals of time, howsoever small these intervals may be.

Class 11 Physics Chapter 3 Related Guides:

Speed and Velocity	Derivation of equation of motion	Frames of Reference
Relative Speed	Uniform Acceleration	Difference between Kinetics and kinematics
Acceleration Time Graph	Path Length	Uniform motion
Average Acceleration Formula	Speed Distance Time Formula	Displacement Formula
Average velocity formula	Average Speed Formula	V-T graphs

Class 11 Physics Study Guides:

NCERT Solutions for Class 11 Physics	Physics Constants	Relation between articles in Physics
Difference between in Physics	Physics Study Notes	SI Units in Physics
Class 11 Physics Notes	Physics Formula	Derivations in Physics

CBSE CLASS XII Related Questions

1.
Answer the following giving reason:
(a) All the photoelectrons do not eject with the same kinetic energy when monochromatic light is incident on a metal surface.
(b) The saturation current in case (a) is different for different intensity.
(c) If one goes on increasing the wavelength of light incident on a metal sur face, keeping its intensity constant, emission of photoelectrons stops at a certain wavelength for this metal.
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2.
The ends of six wires, each of resistance R (= 10 \(\Omega\)) are joined as shown in the figure. The points A and B of the arrangement are connected in a circuit. Find the value of the effective resistance offered by it to the circuit.
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3.
The electric field at a point in a region is given by \( \vec{E} = \alpha \frac{\hat{r}}{r^3} \), where \( \alpha \) is a constant and \( r \) is the distance of the point from the origin. The magnitude of potential of the point is:
- \( \frac{\alpha}{r} \)
- \( \frac{\alpha r^2}{2} \)
- \( \frac{\alpha}{2r^2} \)
- \( -\frac{\alpha}{r} \)
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4.
Figure shows variation of Coulomb force (F) acting between two point charges with \( \frac{1}{r^2} \), \( r \) being the separation between the two charges \( (q_1, q_2) \) and \( (q_2, q_3) \). If \( q_2 \) is positive and least in magnitude, then the magnitudes of \( q_1, q_2 \), and \( q_3 \) are such that:
- \( q_2<q_1<q_3 \)
- \( q_3<q_1<q_2 \)
- \( q_1<q_2<q_3 \)
- \( q_2<q_3<q_1 \)
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5.
A vertically held bar magnet is dropped along the axis of a copper ring having a cut as shown in the diagram. The acceleration of the falling magnet is:
- zero
- less than \( g \)
- \( g \)
- greater than \( g \)
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6.
Write the mathematical forms of three postulates of Bohr’s theory of the hydrogen atom. Using them prove that, for an electron revolving in the \( n \)-th orbit,
(a) the radius of the orbit is proportional to \( n^2 \), and
(b) the total energy of the atom is proportional to \( \frac{1}{n^2} \).
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