Math Problem Statement

Find the laplace transform of the following time function given that the final answer is 1/s^2 - e-Ts/s2 + (-T*e^-2Ts)/s

Solution

To find the Laplace Transform of the given time function f(t)f(t), let's break down the function based on the piecewise definition implied by the graph.

Step 1: Analyze the function

From the graph:

  • For 0t<T0 \leq t < T, f(t)=tTf(t) = \frac{t}{T} (This is a line with slope 1T\frac{1}{T}).
  • For Tt<2TT \leq t < 2T, f(t)=1f(t) = 1 (This is a constant function).
  • For t2Tt \geq 2T, f(t)=0f(t) = 0.

So, the function f(t)f(t) can be represented as:

\frac{t}{T}, & 0 \leq t < T \\ 1, & T \leq t < 2T \\ 0, & t \geq 2T \end{cases}$$ ### Step 2: Express $$f(t)$$ using unit step functions We can express this function in terms of unit step functions $$u(t)$$: $$f(t) = \left( \frac{t}{T} \right) u(t) - \left( \frac{t-T}{T} \right) u(t-T) + u(t-T) - u(t-2T)$$ Simplifying the expression: $$f(t) = \frac{t}{T} u(t) - \frac{t-T}{T} u(t-T) + u(t-T) - u(t-2T)$$ ### Step 3: Find the Laplace Transform of each term Using the Laplace Transform properties: 1. **$$\frac{t}{T} u(t)$$**: $$\mathcal{L}\left\{ \frac{t}{T} u(t) \right\} = \frac{1}{T} \cdot \frac{1}{s^2}$$ 2. **$$-\frac{t-T}{T} u(t-T)$$**: Use the time-shifting property: $$\mathcal{L}\{f(t-T)u(t-T)\} = e^{-Ts} \mathcal{L}\{f(t)\}$$. $$\mathcal{L}\left\{ -\frac{t-T}{T} u(t-T) \right\} = -\frac{1}{T} e^{-Ts} \cdot \frac{1}{s^2}$$ 3. **$$u(t-T)$$**: $$\mathcal{L}\left\{ u(t-T) \right\} = \frac{e^{-Ts}}{s}$$ 4. **$$-u(t-2T)$$**: $$\mathcal{L}\left\{ -u(t-2T) \right\} = -\frac{e^{-2Ts}}{s}$$ ### Step 4: Combine the results The total Laplace Transform is: \[ \mathcal{L}\

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Math Problem Analysis

Mathematical Concepts

Laplace Transform
Piecewise Functions
Unit Step Function
Time Shifting Property

Formulas

Laplace Transform properties

Theorems

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Suitable Grade Level

Advanced Undergraduate