Practice Problems - 12.6 | 12. Inverse Laplace Transform | Mathematics - iii (Differential Calculus) - Vol 1
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Interactive Audio Lesson

Listen to a student-teacher conversation explaining the topic in a relatable way.

Basic Inverse Laplace Transform Problems

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0:00
Teacher
Teacher

Today, we are going to practice finding inverse Laplace transforms. Can anyone remind us of what the inverse Laplace transform does?

Student 1
Student 1

It retrieves a function from its Laplace transform, right?

Teacher
Teacher

Exactly! And how is it represented mathematically?

Student 2
Student 2

It's denoted as f(t) = L⁻¹{F(s)}.

Teacher
Teacher

Great! Let's solve our first problem: Find the inverse Laplace transform of L⁻¹{3s + 4 / s² + 4}.

Student 3
Student 3

I think we could use the standard pairs for transforms.

Teacher
Teacher

Correct! Let's identify the `F(s)` terms here. What do we see?

Student 4
Student 4

We can separate 3s and 4 for evaluation based on known transforms.

Teacher
Teacher

Exactly! Let’s summarize this: we break it down using known pairs. Who can write this solution out?

Partial Fraction Decomposition

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0:00
Teacher
Teacher

Now, let’s discuss using partial fraction decomposition. What is our strategy for these kinds of problems?

Student 1
Student 1

We rewrite F(s) as a sum of simpler fractions!

Teacher
Teacher

That's right! Can anyone give me an example where we can use this method?

Student 2
Student 2

How about L⁻¹{1 / s(s + 2)}?

Teacher
Teacher

Good choice! Can someone show the decomposition step?

Student 3
Student 3

We can express it as 1 / s + A / (s + 2).

Teacher
Teacher

Excellent! Then, we solve for A. Let’s see if we can find A quickly.

Student 4
Student 4

A = -1, right?

Teacher
Teacher

Correct! Now let's wrap up: understanding partial fractions helps us simplify complex inverse Laplace transforms.

Using Convolution Theorem

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0:00
Teacher
Teacher

We’re now looking at the Convolution Theorem for inverse Laplace transforms. Can anyone explain how it works?

Student 1
Student 1

It involves integrating products of two functions.

Teacher
Teacher

Correct! If F(s) = F₁(s) * Fβ‚‚(s), can anyone tell me how to find f(t)?

Student 2
Student 2

We perform the integral from 0 to t of f₁(Ο„) * fβ‚‚(t - Ο„) dΟ„.

Teacher
Teacher

Exactly right! Let’s practice a problem: use convolution to find L⁻¹{1 / (s(s + 1))}.

Student 3
Student 3

We need to identify the components of f₁(s) and fβ‚‚(s) first!

Teacher
Teacher

Perfect! Let’s summarize: Convolution is a powerful tool for finding time-domain functions from frequency domain products.

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section contains practice problems that focus on the methods and applications of the Inverse Laplace Transform.

Standard

In this section, readers will engage with practice problems that reinforce their understanding of finding inverse Laplace transforms using various techniques such as partial fractions and convolution, thereby solidifying their comprehension of theoretical concepts.

Detailed

Inverse Laplace Transform Practice Problems

This section focuses on practical exercises associated with the Inverse Laplace Transform, which is an essential mathematical tool for converting functions from the frequency domain back into the time domain. It is particularly valuable in the fields of engineering and mathematics for solving differential equations. Readers will encounter diverse practice problems aimed at applying the concepts learned regarding the methods of inverse Laplace transforms, including:

  1. Finding direct inverse transforms of specified functions.
  2. Applying partial fraction decomposition on complex rational functions.
  3. Using the Convolution Theorem to find inverse transforms through integrative approaches.

These exercises are designed to enhance the theoretical knowledge by testing the application in practical scenarios.

Audio Book

Dive deep into the subject with an immersive audiobook experience.

Problem 1: Inverse Laplace Transform Calculation

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  1. Find the inverse Laplace transform of
    sΒ² + 4
    L⁻¹{ 3s + 4 }

Detailed Explanation

In this problem, you need to calculate the inverse Laplace transform of the function given in the Laplace domain. The function being used here is (3s + 4)/(sΒ² + 4). To solve it, you would typically decompose it into simpler fractions and use standard inverse Laplace pairs that you have learned.

Examples & Analogies

Think of this problem like baking a cake. The function in the Laplace domain is like a complex recipe. To make it easier, you separate the ingredients into simpler parts, just like breaking down the recipe into manageable steps.

Problem 2: Finding Inverse via Partial Fractions

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  1. Find
    sΒ² + 4s + 5
    { 1 }
    L⁻¹

Detailed Explanation

In this case, you are asked to find the inverse Laplace transform of another function, which requires you to convert the expression into a more tractable form. You would approach this problem by expressing the algebraic fraction into simpler componentsβ€”often involving partial fraction decomposition. Once done, you apply the formulae for the standard inverse transforms to find the time-domain function.

Examples & Analogies

Imagine you are solving a jigsaw puzzle. The expression is like a jigsaw that needs to be separated into pieces before you can see the clear picture. By breaking it down into simple parts, you make it much easier to assemble the final picture of the time-domain function.

Problem 3: Convolution Method Application

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  1. Use convolution to find
    s(s + 1)

Detailed Explanation

For this problem, you will use the convolution theorem to find the inverse Laplace transform of a product of Laplace transforms. You first need to identify the respective functions in the frequency domain that correspond to the Laplace transform given. Following the theorem, you will perform convolution on those functions to retrieve the inverse transform.

Examples & Analogies

Think of the convolution method like mixing two different paints to create a new color. Each paint represents a function in the Laplace domain, and when mixed (convolved), they create a unique result in the time domain. Just like you would carefully measure and mix paints to achieve the desired color, you follow the convolution steps to get the right time-domain function.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Inverse Laplace Transform: Retrieves time-domain functions from their Laplace-transformed expressions.

  • Partial Fraction Decomposition: Simplifies rational functions into a form easier to inverse transform.

  • Convolution Theorem: Relates the inverse of a product of functions to the integral of their pointwise product.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • L⁻¹{3s + 4 / sΒ² + 4} = f(t) = 3e^(-2t) + 4sin(2t).

  • For L⁻¹{1 / (s(s + 1))}, we apply convolution, yielding f(t) = e^(-t)*u(t).

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎡 Rhymes Time

  • When inversing Laplace, don't lose track, find t from s, and take it back!

πŸ“– Fascinating Stories

  • Imagine a library where each function is locked in a box; you need the right key (the inverse transform) to unlock and bring it back to its original state.

🧠 Other Memory Gems

  • Remember 'PCC' - Partial fractions to Convolve to compute to find.

🎯 Super Acronyms

LIFT - Laplace Inverse for Function Time.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Inverse Laplace Transform

    Definition:

    A transformation that retrieves a time-domain function from its Laplace transform.

  • Term: Partial Fraction Decomposition

    Definition:

    A method to express a rational function as a sum of simpler fractions for easier manipulation.

  • Term: Convolution Theorem

    Definition:

    A theorem that states that the inverse Laplace transform of the product of two transforms is the convolution of the corresponding time functions.