How Do You Transform f(t) = cos(t) for t>=2 Using Step Functions?

In summary, the equation f(t) = 0 for t<2 and f(t) = cos(t) for t>=2 can be written as cos(t)u(t-2), where u(t) represents the unit step function. The unit step function becomes 1 when the argument is equal to 0, which is why it becomes 1 when t=2 in this equation.
  • #1
theextractor
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Homework Statement


just trying to get the below equation in terms of step functions, just not sure how to get the cos(t) with the same shifted variable
f(t) = 0 for t<2 f(t)=cos(t) t>=2


The Attempt at a Solution


this is what i got
cos(t)u(t-2)
just having troubles working out the shift for it, had no problems doing this sort of question when it was a multiple of pi, but this has stumped me!
thanks in advance
 
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  • #2
You got it correct, cos(t)u(t-2).
When t = 2, then u(t-2) = u(0), which is where the unit step becomes 1.
 

1. What is a Laplace transform?

A Laplace transform is a mathematical tool used in engineering and physics to convert a function from the time domain to the frequency domain. It is represented by the symbol 'L' and is denoted by L(f(t)) or F(s).

2. How is a Laplace transform calculated?

A Laplace transform is calculated by integrating the function from 0 to infinity, multiplied by the exponential function e^-st. The result is a complex-valued function of the variable 's', which represents the frequency domain.

3. What are the applications of Laplace transform?

Laplace transform is used in various fields such as control systems, signal processing, circuit analysis, and differential equations. It allows us to solve complex problems in the frequency domain, which can then be converted back to the time domain.

4. What is the difference between a one-sided and two-sided Laplace transform?

A one-sided Laplace transform is used for functions that exist only for t ≥ 0, while a two-sided Laplace transform is used for functions that exist for all t. The two-sided transform is more commonly used as it can handle a wider range of functions.

5. What are the advantages of using Laplace transform?

Laplace transform simplifies the solving of complex problems in the frequency domain, making it easier to analyze and understand systems. It also allows us to solve differential equations without using complex integration techniques. Additionally, it has applications in various fields, making it a versatile tool for scientists and engineers.

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