Find the Laplace transforms of the following time functions. Solve problem 1(a) and 1 (b) using the Laplace transform definition i.e. integration. For

Kye

Kye

Answered question

2021-02-21

Find the Laplace transforms of the following time functions.
Solve problem 1(a) and 1 (b) using the Laplace transform definition i.e. integration. For problem 1(c) and 1(d) you can use the Laplace Transform Tables.
a)f(t)=1+2t b)f(t)=sinωtHint: Use Euler’s relationship, sinωt=e(jωt)e(jωt)2j
c)f(t)=sin(2t)+2cos(2t)+etsin(2t)

Answer & Explanation

jlo2niT

jlo2niT

Skilled2021-02-22Added 96 answers

Step 1 

The following functions' Laplace transforms should be determined
The Laplace transforms of the following functions should be identified  L(f(t))=0f(t)estdt 
Step 2 
a) To find the Laplace transform of f(t)=1+2t 
L(f(t))=L(1+2t) 
=0(1+2t)estdt 
=0estdt+0(2t)estdt 
=[ests]0+2[(t)ests][1ests2]0 
=[01s]+2[(00)(01s2] 
=1s+2s2 
=s+2s2 Thus, L(f(t))=s+2s2 
Step 3 
b) To find the Laplace transform of f(t)=sinωt=ejωtejωt2j 
L(f(t))=L(sinωt) 
=0sinωtestdt 
=0ejωtejωt2jestdt =12j0e(jωs)te(jω+s)tdt 
=12j[(e(jωs)t)jωs)(e(jω+s)t(jω+s))]0 
=12j[(e(sjω)t(sjω))(e(jω+s)t(jω+s))]0 
=12j[01(sjω)01(jω+s)] 
=12j[1(sjω)1(jω+s)] 
=12j[1(sjω)1(s+jω)] =12j[(s+jω)(sjω)(sjω)(s+jω)] 
=ωs2(jω)2 
=ωs2+ω2 Since ω2=1 
 

Do you have a similar question?

Recalculate according to your conditions!

New Questions in Differential Equations

Ask your question.
Get an expert answer.

Let our experts help you. Answer in as fast as 15 minutes.

Didn't find what you were looking for?