Access free live classes and tests on the app
Download
+
Unacademy
  • Goals
    • AFCAT
    • AP EAMCET
    • Bank Exam
    • BPSC
    • CA Foundation
    • CAPF
    • CAT
    • CBSE Class 11
    • CBSE Class 12
    • CDS
    • CLAT
    • CSIR UGC
    • GATE
    • IIT JAM
    • JEE
    • Karnataka CET
    • Karnataka PSC
    • Kerala PSC
    • MHT CET
    • MPPSC
    • NDA
    • NEET PG
    • NEET UG
    • NTA UGC
    • Railway Exam
    • SSC
    • TS EAMCET
    • UPSC
    • WBPSC
    • CFA
Login Join for Free
avtar
  • ProfileProfile
  • Settings Settings
  • Refer your friendsRefer your friends
  • Sign outSign out
  • Terms & conditions
  • •
  • Privacy policy
  • About
  • •
  • Careers
  • •
  • Blog

© 2023 Sorting Hat Technologies Pvt Ltd

Watch Free Classes
    • GATE 2024
    • GATE 2024 Question Papers
    • GATE Notes by Jaspal Singh
    • GATE Notes by S K Mondal
    • Downloads
    • GATE 2024 Rank Predictor
    • Notifications
    • MCQs
    • Question Bank
    • Video Lectures
    • Study Materials
    • PSU Recruitment
    • Difference Between
    • Full Forms
    • Exam Tips
    • GATE Books
GATE Exam » GATE Study Materials » Mechanical Engineering » Lagrange’s Equation
Prepare for GATE & ESE

Lagrange’s Equation

In mathematics, the Lagrange equation is a useful tool for solving problems. Avail this comprehensive guide on the same along with examples.

Table of Content
  •  

In mathematics, the Lagrange equation is a useful tool for solving problems. It is used to simplify complex equations and find solutions. In this article, we will discuss how to use Lagrange’s equation to solve problems. We will also provide examples so that you can see how it works in practice. Let’s get started!

What Is Lagrange’s Equation?

Lagrange’s equation is a mathematical way to determine the degree of freedom for a mechanical system. This term, degree of freedom, refers to how many variables you can change and measure in your system. If you want to work with kinematic chains or manipulate objects by their end-effectors, then this is an important concept to understand.

For example, the above image shows a kinematics chain that has three degrees of freedom. You can move each joint or end-effector in three different directions (x, y and z). This means that you can change those variables’ values and measure how they affect your system. A robotic arm, for example, typically has six degrees of freedom.

Lagrange’s Equation Formula

Lagrange’s equation (also known as the Euler–Lagrange equation) is a second-order differential equation that describes the motion of a moving object in space:

L = T −V = m ˙y2/2−mgy

where F(x,y) is any function. When we apply this formula to various problems, it simplifies our calculations.

How to Simplify and Solve for Solutions?

Now that you understand what a degree of freedom is, let’s take a look at how Lagrange’s equation can help simplify the solution process. The equation itself is relatively simple: it’s just a second-order differential equation, where the first derivative is taken with respect to time. This means that we can use a simple substitution method to solve it: just plug in x(t) for y and then solve for t. This will give us an expression of the form:

y = f(x)

where f is some function of x, and t is the time. It should be obvious that y(t) = f(x); this means that we can use Lagrange’s equation to find solutions for any function F(x,y).

The following example will illustrate how this works in practice: suppose you want to solve Lagrange’s linear equation with constant coefficients. This is a very common problem in physics and can be solved using the methods we learned in basic calculus. However, it’s often much easier to use Lagrange’s equation instead. To do this, we need to find the Euler–Lagrange equation for our function F(x,y). In this case, we have:

E = x ˙y−x ˙y+c(x)

We can simplify the above expression by using a simple substitution method. The idea is to replace each term with an equivalent expression that makes solving for y easier. In particular, we’ll use Lagrange’s equation to replace the y terms, and then solve for t. This will give us an expression of the form:

E = x ˙(y)+c(x)

which can be easily solved using basic calculus techniques.

In general, we can say that Lagrange’s equation is a powerful tool for solving problems in physics, and it’s useful to know how to use it. However, we should keep in mind that there are some limitations to this approach: for example, if you want to solve a system of equations involving multiple variables (such as two independent physical quantities), then Lagrange’s equation is not always suitable. In these cases, we need to use a more general approach, such as the differential equation method (which was explained in detail in our previous article on solving Lagrange’s linear equation).

Lagrange Equation Of Motion

The Lagrange equation of motion is a powerful tool for solving problems involving the dynamics of particles and systems of particles. It can be used to determine the motion of a particle or system of particles, given the forces acting on them. The equation is also useful for determining the stability of a system of particles.

The Lagrange equation can be written in the form

F=Mv/t

where M is the total mass of the system, v is the velocity of the particle or system of particles, F is the total force acting on the particle or system of particles, and x is a vector representing position.

The Lagrange equation can be solved for various outcomes by using methods such as Newton’s method or the Euler-Lagrange equation. The Lagrange equation can be used to determine the motion of a particle or system of particles, given forces acting on them.

What does the Euler Lagrange equation show?

Let Ck[a, b] denote the set of continuous functions that define a function on the interval a≤x≤b with its first k derivatives also being continuous on a≤x≤b. The proof needs that the integrand F(x, y, y’) be twice differentiable with respect to each argument.

Conclusion

The beauty of mathematics is that it can be used to solve real-world problems. In this article, we’ve explored one application of mathematics – Lagrange’s equation – and its use in physics. We hope you enjoyed learning about this interesting equation and its history. If you have any questions or want to learn more, please don’t hesitate to reach out to us. Thanks for reading!

Crack GATE with Unacademy

Get subscription and access unlimited live and recorded courses from India’s best educators

  • Structured syllabus
  • Daily live classes
  • Ask doubts
  • Tests & practice
Learn more

Notifications

Get all the important information related to the GATE Exam including the process of application, important calendar dates, eligibility criteria, exam centers etc.

Complete Guide to GATE 2025 Syllabus for CSE with Subject-wise Weightage – Quick Guide
GATE 2012 Questions with Answers
GATE 2013 Question with Answers
GATE 2014 Question with Answers
GATE 2015 Questions with Answers
GATE 2016 Questions with Answers
GATE 2017 Questions with Answers
GATE 2018 Questions with Answers
GATE 2019 Questions with Answers
GATE 2020 Question Paper with Answer: Download PDFs
GATE 2021 Questions with Answers
GATE 2022 Rankers Summit
GATE 2023 Admit Card – Release Date, How to Download & Direct Link
GATE 2023 Exam Dates
GATE 2024 Registration – Application Form at gate2024.iisc.ac.in
GATE CS & IT Engineering Previous Year Questions with Answers
GATE Cutoff 2023 – Brach-wise and Category-wise cut-off
GATE Electrical Engineering Previous Year Questions with Answers
GATE Electronics and Communication Engineering (ECE) Previous Year Questions with Answers
GATE Exam Calendar 2023
GATE Exam Eligibility 2024 – Age Limit, Qualification, Number of Attempts
GATE Exam Pattern 2023 – New Test Structure, Paper Pattern, Marking Scheme for all papers
GATE Mechanical Engineering Previous Year Questions with Answers
GATE Previous Year Question Papers with Solution – Download PDFs
GATE Previous Year Question Papers with Solutions for Civil Engineering
GATE Result 2023 Out – Steps to check GATE Result
GATE Syllabus 2026: Download GATE Syllabus PDF
See all

Related articles

Learn more topics related to Mechanical Engineering
Zeroth and First Laws of Thermodynamics

The branch of physical science that deals with the relationship between heat and all the other forms of energy is Thermodynamics.

Winds: Headwinds, Tailwinds, and Crosswinds

This write-up is based on the introduction about the topic, Definition of Tailwinds, definition of headwinds, and definition of crosswinds.

Wet Bulb Depression

The difference between the temperature of the dry bulb and the temperature of the wet bulb is referred to as the wet-bulb depression.

Wave and Laplace’s Equations

The wave equation, heat equation, and Laplace's equation are known as three essential conditions in numerical material science and happen in many parts of physical science, in applied arithmetic as well as in designing or engineering.

See all
Access more than

10,997+ courses for GATE & ESE

Get subscription

Related links

  • GATE 2024 Rank Predictor
  • GATE Syllabus
  • GATE 2024 Question Papers with Solutions
  • GATE Previous Year Question Paper
  • GATE Preparation
  • GATE Civil Engineering Syllabus
  • GATE Previous Year Question Papers with Solutions for ECE
  • GATE 2020 Question Paper
  • GATE 2022 Question Paper
  • GATE Eligibility
  • GATE Exam Calender
  • GATE Results
  • GATE Books
  • GATE Notes

Trending Topics

  • GATE 2024
  • GATE Syllabus 2024
  • GATE Registration
  • How to Prepare for GATE Exam
  • GATE Exam Tips
  • GATE MCQs
  • GATE Question Bank
  • PSU Recruitment
practicewithpyqs_gate
Download previous years papers
.
Company Logo

Unacademy is India’s largest online learning platform. Download our apps to start learning


Starting your preparation?

Call us and we will answer all your questions about learning on Unacademy

Call +91 8585858585

Company
About usShikshodayaCareers
we're hiring
BlogsPrivacy PolicyTerms and Conditions
Help & support
User GuidelinesSite MapRefund PolicyTakedown PolicyGrievance Redressal
Products
Learner appLearner appEducator appEducator appParent appParent app
Popular goals
IIT JEEUPSCSSCCSIR UGC NETNEET UG
Trending exams
GATECATCANTA UGC NETBank Exams
Study material
UPSC Study MaterialNEET UG Study MaterialCA Foundation Study MaterialJEE Study MaterialSSC Study Material

© 2025 Sorting Hat Technologies Pvt Ltd

Unacademy
  • Goals
    • AFCAT
    • AP EAMCET
    • Bank Exam
    • BPSC
    • CA Foundation
    • CAPF
    • CAT
    • CBSE Class 11
    • CBSE Class 12
    • CDS
    • CLAT
    • CSIR UGC
    • GATE
    • IIT JAM
    • JEE
    • Karnataka CET
    • Karnataka PSC
    • Kerala PSC
    • MHT CET
    • MPPSC
    • NDA
    • NEET PG
    • NEET UG
    • NTA UGC
    • Railway Exam
    • SSC
    • TS EAMCET
    • UPSC
    • WBPSC
    • CFA

Share via

COPY