Get plus subscription and access unlimited live and recorded courses

A vector is a two-dimensional element containing magnitude and direction both. A vector can be visualized geometrically as a directed line segment with an arrow indicating the vector's direction and a length equal to the vector's magnitude, from the tail to the head of the vector indicating the direction.

In the chapter Vector, we will learn about the basics of the vector-like types, definition, And solved examples along with some previous year's questions for better understanding.

Addition of Vectors

Multiplication of Vector with Scalar

Types of Vector

Scalar Triple Product

Vectors are geometric representations of magnitude and direction, generally depicted as straight lines that start at one point on a coordinate axis and finish at another. Every vector has a length, known as the magnitude, that indicates some quality of interest so that it can be compared to another vector. Because vectors are arrows, they have a direction. This distinguishes them from scalars, which are just numbers with no meaning.

The magnitude and orientation of a vector with respect to a set of coordinates define it. Breaking down vectors into their component pieces is frequently beneficial when examining vectors. These components are horizontal and vertical for two-dimensional vectors. For three dimensional vectors, the magnitude component is the same, but the direction component is expressed in terms of $\text{x}$, $\text{y}$ and $\text{z}$.

In mathematics, a vector is a geometric entity with both magnitude and direction. Vectors have a starting point at which they begin and a terminal point that indicates the point's final position. Addition, subtraction, and multiplication are some of the operations that can be performed on vectors.

In physics, vectors are extremely significant. Velocity, displacement, acceleration, and force, for example, are all vector quantities with both a magnitude and a direction.

The Magnitude of Vectors

The square root of the sum of the squares of a vector's components can be used to calculate its magnitude. If $\left(x,y,z\right)$ are the components of a vector $\text{A}$, then the magnitude formula of A is given by, $\left|A\right|=\sqrt{{x}^{2}+{y}^{2}+{z}^{2}}$

A vector's magnitude is a scalar value.

Angle Between Two Vectors

The dot product formula can be used to calculate the angle between two vectors. Let us consider two vectors a and b and the angle between them to be $\theta $. Then, the dot product of two vectors can be given by a·b = |a||b| cosθ, we need to determine the value of the angle $\theta $. The direction of the two vectors is also shown by the angle between the two vectors. $\theta $ can be evaluated using the following formula:

θ = cos-1[(a·b)/|a||b|]

A scalar is a non-directional real number. When a scalar is multiplied by a vector, each component of the vector is multiplied by the scalar. Scalar multiplication is the process of multiplying a vector by a scalar. When a vector a = (${a}_{1},{a}_{2},{a}_{3}$) = ${a}_{1}\hat{i}$ + ${a}_{2}\hat{j}$ + ${a}_{3}\hat{k}$ is multiplied by a scalar r, the resultant vector is:

ra = ($r{a}_{1},r{a}_{2},r{a}_{3}$) = ($r{a}_{1}$)e1 + ($r{a}_{2}$)e2 + ($r{a}_{3}$)e3

If r is negative, the resultant vector's direction changes by 180 degrees.

Scalar multiplication is distributive over vector addition, that is, r(a+b) = ra + rb

Scaling is defined as the multiplication of vectors by any scalar quantity. In vectors, scaling only affects the magnitude and not the direction. Some properties of scalar multiplication in vectors are given below:

k(a + b) = ka + kb

(k + l)a = ka + la

a·1 = a

a·0 = 0

a·(-1) = -a

It's one vector's dot multiplied by the cross product of the other two vectors. In a scalar triple product, if any two vectors are equal, the scalar triple product is zero. The three vectors a, b, and c are said to be coplanar if the scalar triple product is equal to zero. Also, a·(b × c) = b·(c × a) = c·(a × b)

To get the dot product of two vectors, multiply the individual components of the two vectors to be multiplied and add the result.

a·b = (${a}_{1}\hat{i}$ + ${b}_{1}\hat{j}$ + ${c}_{1}\hat{k}$) ·(${a}_{2}\hat{i}$ + ${b}_{2}\hat{j}$ + ${c}_{2}\hat{k}$) = (${a}_{1},{b}_{1},{c}_{1}$)·(${a}_{2},{b}_{2},{c}_{2}$) = (${a}_{1}\xb7{a}_{2}$) + (${b}_{1}\xb7{b}_{2}$) + (${c}_{1}\xb7{c}_{2}$)

The product of the magnitudes of the two vectors and the cosine of the angle between them is another technique to find the dot product of two vectors A and B.

$\overrightarrow{A}\xb7\overrightarrow{B}$ = |A||B| cosθ

The resultant of a dot product of two vectors is a scalar value, that is, it has no direction.

The vector components are represented by a matrix, and the result of the cross product of the vectors is represented by a determinant of the matrix.

$\overrightarrow{A}\times \overrightarrow{B}$ = (${b}_{1}{c}_{2}-{c}_{1}{b}_{2},{a}_{1}{c}_{2}-{c}_{1}{a}_{2},{a}_{1}{b}_{2}-{b}_{1}{a}_{2}$)

The product of the magnitudes of the two vectors and the sine of the angle between them is another technique to find the cross product of two vectors A and B.

$\overrightarrow{A}\times \overrightarrow{B}$ = |A||B| sinθ $\hat{n}$

Properties of vector

The properties of vectors listed below helps in understanding vectors and are useful in conducting a variety of mathematical operations using vectors.

The addition of vectors is commutative and associative.

$\overrightarrow{A}.\overrightarrow{B}=\overrightarrow{B}.\overrightarrow{A}$

$\overrightarrow{A}\times \overrightarrow{B}\ne \overrightarrow{B}\times \overrightarrow{A}$

$\hat{i}.\hat{i}=\hat{j}.\hat{j}=\hat{k}.\hat{k}=1$

$\hat{i}.\hat{j}=\hat{j}.\hat{k}=\hat{k}.\hat{i}=0$

$\hat{i}\times \hat{i}=\hat{j}\times \hat{j}=\hat{k}\times \hat{k}=0$

$\hat{i}\times \hat{j}=\hat{k}\text{};\text{}\hat{j}\times \hat{k}=\hat{i}\text{};\text{}\hat{k}\times \hat{i}=\hat{j}$

$\hat{j}\times \hat{i}=-\hat{k}\text{};\text{}\hat{k}\times \hat{j}=-\hat{i}\text{};\text{}\hat{i}\times \hat{k}=-\hat{j}$

The scalar dot product of two vectors lies in the plane of the two vectors and is a scalar.

A vector that is perpendicular to the plane containing two vectors is the cross product of two vectors.

Vectors can be used to represent physical quantities. In physics, vectors are commonly employed to express displacement, velocity, and acceleration. Vectors are arrows that represent a magnitude and direction combination. The length represents the magnitude, while the vector's pointing direction represents the direction of that quantity. Because vectors are formed in this way, physical quantities (with both size and direction) can be analysed as vectors.

Vectors are useful in physics because they can represent location, displacement, velocity, and acceleration visually. Because you often don't have enough room to draw vectors to the scale they represent when drawing them, it's critical to know what scale you're working with. For example, consider when drawing a vector that represents a magnitude of 100, one may draw a line that is 5 units long at a scale of $\frac{1}{20}$. When the drawn magnitude is multiplied by the inverse of the scale, the result should equal the real magnitude.

Si.no | Name of the Concept | Formulae |

Magnitude of two dimensional Vector | |a| = $\sqrt{{a}_{1}^{2}+{a}_{2}^{2}}$ | |

Magnitude of three dimensional Vector | |a| = $\sqrt{{a}_{1}^{2}+{a}_{2}^{2}+{a}_{3}^{2}}$ | |

Dot product of the vector | $\overrightarrow{A}\xb7\overrightarrow{B}$ = |A||B| cosθ | |

Cross product of the vector | $\overrightarrow{A}\times \overrightarrow{B}$ = (${b}_{1}{c}_{2}-{c}_{1}{b}_{2},{a}_{1}{c}_{2}-{c}_{1}{a}_{2},{a}_{1}{b}_{2}-{b}_{1}{a}_{2}$) |

Example 1: Find the sum of two vectors a = 4 $\hat{i}$ + 2 $\hat{j}$ – 5 $\hat{k}$ and b = 3 $\hat{i}$ – 2$\hat{j}$ + $\hat{k}$ ?

Solution:

Given two vectors a = 4 $\hat{i}$ + 2 $\hat{j}$ – 5$\hat{k}$ and b = 3$\hat{i}$ – 2$\hat{j}$ + $\hat{k}$

a + b = (4$\hat{i}$ + 2$\hat{j}$ – 5$\hat{k}$) + (3$\hat{i}$ – 2$\hat{j}$ + $\hat{k}$)

= (4 + 3)$\hat{i}$ + (2 - 2)$\hat{j}$ + (-5 + 1)$\hat{k}$

= 7$\hat{i}$ + 0 $\hat{j}$ - 4$\hat{k}$

= 7$\hat{i}$ - 4 $\hat{k}$

Therefore, the sum of two vectors is 7 $\hat{i}$ - 4 $\hat{k}$

Answer: 7 $\hat{i}$ - 4 $\hat{k}$

Example 2: Find the cross product of two vectors a = 4 $\hat{i}$ + 2$\hat{j}$ -5$\hat{k}$ and b = 3 $\hat{i}$ -2$\hat{j}$ + $\hat{k}$ and verify it using cross product calculator?

Solution:

Given two vectors a = 4 $\hat{i}$ + 2$\hat{j}$ – 5$\hat{k}$ and b = 3 $\hat{i}$ – 2$\hat{j}$ + $\hat{k}$

Comparing these to the vector notations we have.

a = ${a}_{1}\hat{i}+{a}_{2}\hat{j}+{a}_{3}\hat{k}$ and b = ${b}_{1}\hat{i}+{b}_{2}\hat{j}+{b}_{3}\hat{k}$

Applying cross product formula,

a × b = $\hat{i}$(a2b3 − a3b2) − $\hat{j}$(a1b3 − a3b1) + $\hat{k}$(a1b2 − a2b1)

= $\hat{i}$((2 × 1) - (-5) × (-2)) - $\hat{j}$((4 × 1 - (-5) × (3)) + $\hat{k}$((4) × (-2) - (2 × 3))

= $\hat{i}$(2 - 10) - $\hat{j}$(4 + 15) + $\hat{k}$(-8 - 6)

= -8$\hat{i}$ - 19$\hat{j}$ - 14$\hat{k}$

Therefore, the cross product of two vectors is -8$\hat{i}$ - 19$\hat{j}$ - 14$\hat{k}$

Answer: -8$\hat{i}$ - 19$\hat{j}$ - 14$\hat{k}$

Question 1: Let O be the origin and OX, OY, OZ be three unit vectors in the direction of the sides QR, RP, PQ respectively of a triangle PQR. If the triangle PQR varies, then the minimum value of cos (P+Q) + cos(Q+R) + cos (R+P) is

(a) 3/2

(b) -3/2

(c) 5/3

(d) -5/3

Solution:

In triangle PQR, P+Q+R = π

P+Q = π-R

Q+R = π-P

P+R = π-Q

cos (π-R)+ cos (π-P)+ cos (π-Q) = -cos R – cos P – cos Q

To minimize the given expression, we should maximize cos P+cos Q+cos R.

cos P+cos Q+cos R will be maximum when cos P = cos Q = cos R

=>P = Q = R = π/3

=> PQR is equilateral triangle.

So minimum value = -3 cos π/3

= -3/2

Hence option b is the answer.

Question 2: Let O be the origin and OX, OY, OZ be three unit vectors in the direction of the sides QR, RP, PQ respectively of a triangle PQR.

$\begin{array}{l}\left|\overrightarrow{OX}\times \overrightarrow{OY}\right|\end{array}$

equals

(a) sin (Q+R)

(b) sin (P+R)

(c) sin 2R

(d) sin (P+Q)

Solution:

$\begin{array}{l}\left|\overrightarrow{OX}\times \overrightarrow{OY}\right|=\left|\overrightarrow{OX}\right|\left|\overrightarrow{OY}\right|\mathrm{sin}\theta \end{array}$

= 1×1×sin θ

= sin (180-R)

= sin (P+Q)

Hence option d is the answer.

Question 3: Let $\begin{array}{l}\overrightarrow{a}=2\hat{i}+{\lambda}_{1}\hat{j}+3\hat{k}\end{array}$, $\begin{array}{l}\overrightarrow{b}=4\hat{i}+(3-{\lambda}_{2})\hat{j}+6\hat{k}\end{array}$ and $\begin{array}{l}\overrightarrow{c}=3\hat{i}+6\hat{j}+({\lambda}_{3}-1)\hat{k}\end{array}$

be three vectors such that $\begin{array}{l}\overrightarrow{b}=2\overrightarrow{a}\end{array}$

and vector a is perpendicular to vector c. then a possible value of λ1, λ2, λ3 is

(a) (1, 3, 1)

(b) (-½, 4, 0)

(c) (½, 4, -2)

(d) (1, 5, 1)

Solution:

Given that

$\begin{array}{l}\overrightarrow{b}=2\overrightarrow{a}\end{array}$

So 4i+(3-λ2)j + 6k = 4i + 2λ1j + 6k (i, j, k are the unit vectors)

So (3-λ2) = 2λ1 ..(i)

Vector a is perpendicular to vector c.

So

$\begin{array}{l}\overrightarrow{a}.\overrightarrow{c}=0\end{array}$

6+6λ1+3(λ3-1) = 0

=> 2 + 2λ1 + λ3-1 = 0

=> λ3 = -2λ1 – 1 ..(ii)

Check the options.

(-½, 4, 0) satisfies (i) and (ii).

So possible value of λ1, λ2, λ3 are (-½, 4, 0).

Hence option b is the answer.

Q1. Let $\overrightarrow{\mathrm{x}},\overrightarrow{\mathrm{y}}$ and $\overrightarrow{\mathrm{z}}$ be three vectors each of magnitude $\sqrt{2}$ and the angle between each pair of them is $\frac{\pi}{3}.$ If $\overrightarrow{\mathrm{a}}$ is a nonzero vector perpendicular to $\overrightarrow{\mathrm{x}}$ and $\overrightarrow{\mathrm{y}}\times \overrightarrow{\mathrm{z}}$ and $\overrightarrow{\mathrm{b}}$ is nonzero vector perpendicular to $\overrightarrow{\mathrm{y}}$ and $\overrightarrow{\mathrm{z}}\times \overrightarrow{\mathrm{x}},$ then

(A) $\overrightarrow{\mathrm{b}}=(\overrightarrow{\mathrm{b}}\cdot \overrightarrow{\mathrm{z}})(\overrightarrow{\mathrm{z}}-\overrightarrow{\mathrm{x}})$

(B) $\overrightarrow{\mathrm{a}}=(\overrightarrow{\mathrm{a}}\cdot \overrightarrow{\mathrm{y}})(\overrightarrow{\mathrm{y}}-\overrightarrow{\mathrm{z}})$

(C) $\overrightarrow{\mathrm{a}}\cdot \overrightarrow{\mathrm{b}}=-(\overrightarrow{\mathrm{a}}\cdot \overrightarrow{\mathrm{y}})(\overrightarrow{\mathrm{b}}\cdot \overrightarrow{\mathrm{z}})$

(D) $\phantom{\rule{1em}{0ex}}\overrightarrow{a}=(\overrightarrow{a}\cdot \overrightarrow{y})(\overrightarrow{z}-\overrightarrow{y})$

Answer: C

Q. Let $\mathrm{\Delta}\mathrm{P}\mathrm{Q}\mathrm{R}$ be a triangle. Let $\overrightarrow{\mathrm{a}}=\overrightarrow{\mathrm{Q}\mathrm{R}},\overrightarrow{\mathrm{b}}=\overrightarrow{\mathrm{R}\mathrm{P}}$ and $\overrightarrow{\mathrm{c}}=\overrightarrow{\mathrm{P}\mathrm{Q}}.$ If $|\overrightarrow{\mathrm{a}}|=4\sqrt{3}$ and $\overrightarrow{\mathrm{b}.\overrightarrow{\mathrm{c}}}=24$ then which of the following is (are) true?

(A) $\frac{|\overrightarrow{\mathrm{c}}{|}^{2}}{2}-|\overrightarrow{\mathrm{a}}|=12$

(B) $\frac{|\overrightarrow{\mathrm{c}}{|}^{2}}{2}+|\overrightarrow{\mathrm{a}}|=30$

(C) $|\overrightarrow{\mathrm{a}}\times \overrightarrow{\mathrm{b}}+\overrightarrow{\mathrm{c}}\times \overrightarrow{\mathrm{a}}|=48\sqrt{3}$

(D) $\overrightarrow{\mathrm{a}}\cdot \overrightarrow{\mathrm{b}}=-72$

Answer: B

A vector is defined as an object that has both directions and magnitude in general. In this post, we'll look at several types of vectors, as well as vector operations and applications. Also, for a better grasp of the subject, we went through some of the solved examples and previous year's problems.

See More

JEE Advanced 2022 exam date and revised schedule have been announced by the NTA. JEE Advanced 2022 will now be conducted on 28-August-2022, and the exam registration closes on 11-August-2022. You can check the complete schedule on our site. Furthermore, you can check JEE Advanced 2022 dates for application, admit card, exam, answer key, result, counselling, etc along with other relevant information.

See More

View All Dates

Application Form

Eligibility Criteria

Reservation Policy

Admit Card

IIT Bombay has announced the JEE Advanced 2022 application form release date on the official website https://jeeadv.ac.in/. JEE Advanced 2022 Application Form is available on the official website for online registration. Besides JEE Advanced 2022 application form release date, learn about the application process, steps to fill the form, how to submit, exam date sheet etc online. Check our website for more details.

It is crucial for the the engineering aspirants to know and download the JEE Advanced 2022 syllabus PDF for Maths, Physics and Chemistry. Check JEE Advanced 2022 syllabus here along with the best books and strategies to prepare for the entrance exam. Download the JEE Advanced 2022 syllabus consolidated as per the latest NTA guidelines from Vedantu for free.

See More

Download full syllabus

Download full syllabus

View JEE Advanced Syllabus in Detail

JEE Advanced 2022 Study Materials: Strengthen your fundamentals with exhaustive JEE Advanced Study Materials. It covers the entire JEE Advanced syllabus, DPP, PYP with ample objective and subjective solved problems. Free download of JEE Advanced study material for Physics, Chemistry and Maths are available on our website so that students can gear up their preparation for JEE Advanced exam 2022 with Vedantu right on time.

See More

All

Chemistry

Maths

Physics

See All

Download JEE Advanced Question Papers & Answer Keys of 2022, 2021, 2020, 2019, 2018 and 2017 PDFs. JEE Advanced Question Paper are provided language-wise along with their answer keys. We also offer JEE Advanced Sample Question Papers with Answer Keys for Physics, Chemistry and Maths solved by our expert teachers on Vedantu. Downloading the JEE Advanced Sample Question Papers with solutions will help the engineering aspirants to score high marks in the JEE Advanced examinations.

See More

In order to prepare for JEE Advanced 2022, candidates should know the list of important books i.e. RD Sharma Solutions, NCERT Solutions, HC Verma books and RS Aggarwal Solutions. They will find the high quality readymade solutions of these books on Vedantu. These books will help them in order to prepare well for the JEE Advanced 2022 exam so that they can grab the top rank in the all India entrance exam.

See More

See All

JEE Advanced 2022 free online mock test series for exam preparation are available on the Vedantu website for free download. Practising these mock test papers of Physics, Chemistry and Maths prepared by expert teachers at Vedantu will help you to boost your confidence to face the JEE Advanced 2022 examination without any worries. The JEE Advanced test series for Physics, Chemistry and Maths that is based on the latest syllabus of JEE Advanced and also the Previous Year Question Papers.

See More

IIT Bombay is responsible for the release of the JEE Advanced 2022 cut off score. The qualifying percentile score might remain the same for different categories. According to the latest trends, the expected cut off mark for JEE Advanced 2022 is 50% for general category candidates, 45% for physically challenged candidates, and 40% for candidates from reserved categories. For the general category, JEE Advanced qualifying marks for 2021 ranged from 17.50%, while for OBC/SC/ST categories, they ranged from 15.75% for OBC, 8.75% for SC and 8.75% for ST category.

See More

JEE Advanced 2022 Result - IIT Bombay has announced JEE Advanced result on their website. To download the Scorecard for JEE Advanced 2022, visit the official website of JEE Advanced i.e https://jeeadv.ac.in/.

See More

Rank List

Counselling

Cutoff

Want to know which Engineering colleges in India accept the JEE Advanced 2022 scores for admission to Engineering? Find the list of Engineering colleges accepting JEE Advanced scores in India, compiled by Vedantu. There are 1622 Colleges that are accepting JEE Advanced. Also find more details on Fees, Ranking, Admission, and Placement.

See More

FAQ

**1. What is the Difference Between Scalars and Vectors?**

Scalars are things that have magnitude but not direction, whereas vectors are objects that have both magnitude and direction. Real values with units of measurement are commonly referred to as scalars. The direction in which an object is travelling is indicated by vectors. Time 4 hours, for example, is a scalar because it has no direction, whereas a velocity 40 mph is a vector since it indicates that the item is going in one direction.

**2. How are Vectors used in Real Life?**

In everyday life, vectors are commonly employed to express the velocity of an aircraft when both the aircraft's speed and direction of movement must be understood. Electromagnetic induction is the result of the interaction of electric and magnetic forces.

**3. What is the importance of chapter Vector in JEE Advance?**

Every year you will get 1 - 2 questions in JEE Main exam as well as in other engineering entrance exams. This chapter helps you with 3-D Geometry and Physics (Kinematics, Work, Energy and Power, electrostatics, etc.).

Last date to download admit card

28 Sep 2022•3 days remaining

News

Blog

Trending pages