# Motion in a Plane Class 11th Notes - Free NCERT Class 11 Physics Chapter 4 notes - Download PDF

Physical variables such as force, acceleration, and displacement are represented by both magnitude and direction, unlike temperature, work, and distance, which can only be represented by magnitude. This is the subject of Class 11 Physics chapter 4 motion in a plane. You can go to motion in a plane Class 11 notes if you're having trouble grasping particular ideas in this chapter. The Class 11 Physics chapter 4 notes can also be extremely useful in the run-up to the exams.

The definitions of velocity, acceleration, and magnitude are covered in the first section of Class 11 Physics chapter 4 notes. Study the motion in a plane Class 11 notes pdf download to learn about the key terminology and their definitions in Physics.

Students will learn about various plane motions such as circular motion, projectile motion, and so on. In Class 11 motion in a plane notes, the equations for motion in a straight line are also used in the x and y directions to figure out the equations for motion in a plane.

You will gain a comprehensive understanding of projectile motion by studying CBSE Class 11 Physics chapter 4 notes (a special type of motion in a plane). The motion in a plane Class 11 notes also includes a number of projectile motion examples.

This section of NCERT Class 11 Physics chapter 4 notes covers the differences and properties of scalar and vector quantities, as well as their definitions. In addition, NCERT notes for Class 11 Physics chapter 4 explain unit vectors, equal vectors, zero vectors, negative of a vector, parallel vectors, displacement vectors, and coplanar vectors.

In this section of notes for Class 11 Physics chapter 4, students will learn how to resolve a vector and what the resolution process entails. In the domain of physics, vectors are resolved using x, y, and z coordinates. Following that are the vector addition and subtraction techniques. In Motion in a Plane Class 11 notes, both geometrical and analytical methods are thoroughly explored, allowing you to gain a thorough understanding of the subject.

The explanation of relative motion velocity begins this portion of Chapter 4 Physics Class 11 notes. Following that, in the Motion in a Plane Class 11 notes, you'll learn about 2D relative motion velocity, which is explained with a precise and easy derivation.

The last portion of Motion in a Plane Class 11 notes focus on uniform circular motion and the variables that are used to describe it, such as angular displacement, angular acceleration, angular velocity, and centripetal acceleration. More about projectile motion is discussed later in this portion of Class 11 Physics chapter 4 notes, including 2D projectiles, important characteristics of projectile motion, and so on.

**Also, students can refer,**

- NCERT Solutions for Class 11 Physics Chapter 4 Motion in a Plane
- NCERT Exemplar class 11 physics chapter 4 Motion in a Plane

**1. SCALARS AND VECTORS**

A unique number can be used to describe some values. A single number can be used to indicate mass, time, distance, and speed, for example. Scalar quantities are what they're termed.

One piece of information is insufficient to convey how to travel to a location from another location. Both distance and displacement are required to fully express this.

Vectors are quantities that require both magnitude and direction to accurately represent a situation. Vectors include things like displacement and velocity.

The vectors are shown by an arrow over the symbols that represent them.

For example,

Unit vector:

Because a unit vector has a magnitude of one, it only provides the vector's direction.

By dividing the original vector by its magnitude, a unit vector can be found.

Addition, subtraction and scalar multiplication of vectors:

Consider two vectors as follows:

Then,

Multiplication of a vector by scalar quantity:

Magnitude and direction

Parallel vectors:

If and only if two vectors have the same direction, they are said to be parallel vectors. When a vector is multiplied by a scalar, the result is a vector that is parallel to the original vector.

If b=ka then b and a are parallel vectors.

Equality of vectors:

When the magnitudes and directions of two vectors (indicating two values of the same physical quantity) are the same, they are said to be equal.

1.5 Subtraction of vectors:

Let a^{'} and b^{'}are two vectors. We define a'-b^{' }as the sum of vectors a^{'} and (-b)^{'}

1.6 Dot product or scalar product of two vectors:

Dot products of a^{'} and b^{'} is given by

If θ=0

If θ=90^{o}

Dot product of unit vectors are given by

Similarly

Now,

Similarly

Dot products are commutative and distributive:

**2. MOTION IN 2D (PLANE)**

2.1 Position vector and Displacement:

The position vector of a particle P on a plane with respect to the origin of xy–coordinate system is given by

Now, if the particle moves along the path to a new position P_{1} with the position vector r;

Displacement

2.2 Average velocity:

2.3 Instantaneous velocity:

2.4 Average acceleration:

2.5 Instantaneous acceleration:

**3. PROJECTILE MOTION**

When a particle is propelled obliquely close to the earth's surface, it moves in both horizontal and vertical directions at the same time. Projectile motion is the name given to the movement of such a particle.

Horizontal axis | Vertical axis |

Maximum Range:

Range is maximum when sin2θ is maximum

3.1 Equation of trajectory:

The path taken by the body is referred to as trajectory. To establish the trajectory, we must eliminate time and find the relationship between y and x.

Horizontal Motion | Vertical Motion |

**4. RELATIVE MOTION**

Case I: If you see a car going on a straight road, you say the automobile's velocity is 20 mph, which implies the car's velocity relative to you is 20 mph, or the car's velocity relative to the ground is 20 mph (as you stand on the ground).

Case II: If you look inside this car, you'll notice that it's at a standstill while the road is moving backwards. Then you'd say the car's velocity in relation to the car is 0m/s.

Mathematically, velocity of B relative to A is represented as

**5. RIVERBOAT PROBLEMS**

We come across the following three terms when dealing with riverboat issues:

v_{r}^{'}= the river's absolute velocity

v_{br}^{'}= a boatman's velocity in relation to the river, or a boatman's velocity in still water

v_{b}^{'}=boatman’s absolute velocity

**Significance of NCERT Class 11 Physics Chapter 4 Notes**

Motion in a plane Class 11 notes would be beneficial to revise the chapter and to acquire an understanding about the major issues presented in the chapter. This NCERT Class 11 Physics chapter 4 notes are also beneficial for competitive exams such as VITEEE, BITSAT, JEE Main, NEET, and others, as they cover the main themes of the CBSE Physics Syllabus. You can use the Class 11 Physics chapter 4 notes pdf download to study offline.

**NCERT Class 12 Notes Chapter-Wise**

**Subject Wise NCERT Exemplar Solutions**

- NCERT Exemplar Class 11 Solutions
- NCERT Exemplar Class 11 Maths
- NCERT Exemplar Class 11 Physics
- NCERT Exemplar Class 11 Chemistry
- NCERT Exemplar Class 11 Biology

**Subject Wise NCERT Solutions**

- NCERT Solutions for Class 11 Mathematics
- NCERT Solutions for Class 11 Chemistry
- NCERT Solutions for Class 11 Physics

## Frequently Asked Question (FAQs) - Motion in a Plane Class 11th Notes - Free NCERT Class 11 Physics Chapter 4 notes - Download PDF

**Question: **Explain one-dimensional motion

**Answer: **

In ncert notes for Class 11 Physics chapter 4 Only a single coordinate determines the position of each item in one-dimensional motion. Only one plane out of three depicts the movement of an object with respect to the starting point or origin in this sort of motion. Some instances are as follows: an automobile moving in a straight line, a train moving in a straight line, a man cycling on a straight road, an object falling on the ground in a straight line due to gravity

**Question: **What do you mean by tensor?

**Answer: **

In ncert Class 11 Physics chapter 4 notes the term tensor refers to a physical quantity that has no direction. Instead, it has a variety of values pointing in diverse directions. As a result, it is neither a scalar nor a vector quantity. A moment of inertia of any object, for example, has no direction but a variety of values in different directions. As a result, it is neither a scalar nor a vector quantity. It is an illustration of a tensor. Tensors include stress, density, strain, and refractive index, among others.

**Question: **Identify whether the statement is correct or incorrect. A position vector is a displacement vector.

**Answer: **

The following statement is correct: "a displacement vector is a location vector." In class 11th physics chapter 4 notes the position or condition of any point that is similar to the position vector is represented by a displacement vector. To some extent, the position and displacement vectors are comparable. The displacement vector differs from the position vector in that it describes the position of any point in relation to other points rather than the origin. The position vector, on the other hand, specifies the position of any point in relation to the origin. This is how the truth of the statement is demonstrated.

**Question: **What are the Laws of Motion?

**Answer: **

The three fundamental laws of motion are: I All things or devices travel in a straight or linear direction unless an external force acts on them; (ii) Force applied to a body is directly proportional to the mass and acceleration of the body; and (iii) All actions have an equal and opposite reaction.

**Question: **What are the Types of Motion according to Motion in a plane Class 11 notes pdf download?

**Answer: **

In Class 11 Physics chapter 4 notes all mechanical devices, in general, start with an input motion and then modify the force to produce an output motion, which can be rotary, linear, oscillating, or reciprocating. To begin, rotary motion is defined as motion that revolves around an axis or a fixed joint, such as a wheel. Second, linear motion is defined as movement that occurs in a straight line, such as train travel. Finally, oscillating motion can be defined as the movement of a stationary axis forward and backward. Finally, reciprocating motion is defined as repeating back-and-forth or down-and-up action

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