laplace transform mcq 100 questions with solution
🔵 Laplace Transform
100 MCQs with Detailed Step-by-Step Solutions
Here,
Therefore:
Integrating:
Applying the limits:
For s > 0:
Hence:
Here:
Therefore:
Since 1! = 1:
Put n = 2:
Since:
Therefore:
Now:
Therefore:
Using the definition:
Combine the exponential terms:
Therefore:
Start with:
Replace a by −a:
Therefore:
The standard Laplace transform of sin(at) is:
For example, if a = 3:
Using the standard Laplace transform:
For example:
Use the identity:
Taking Laplace transform:
Taking common denominator:
Use:
Taking Laplace transform:
After simplifying:
Given:
Therefore:
Using the constant multiplication property:
Since L{f(t)} = F(s):
Using linearity:
Now:
Therefore:
We know:
Therefore:
Also:
Hence:
Here a = 2.
Multiplying by 5:
Use:
Here a = 2:
Multiply by 3:
For a = 3:
Multiply by 4:
Since:
Therefore:
We know:
Therefore:
We know:
Therefore:
By the derivative property of the Laplace transform:
Since:
we get:
The initial value f(0) is therefore included automatically in the transformed derivative.
We know:
Apply the same derivative rule again:
Substitute:
Expand:
From the second derivative:
Now take the transform of the third derivative:
Substitute the previous result:
Expand:
Given:
Using the formula:
Substitute f(0) = 2:
Given:
Substitute into the derivative formula:
Therefore:
🔵 Laplace Transform
100 MCQs with Detailed Step-by-Step Solutions
Suppose:
Differentiate F(s) with respect to s:
Therefore:
For n = 2:
Since (−1)² = 1:
We know:
Therefore:
Differentiate:
Since L{tf(t)} = −F′(s):
Let:
Differentiate with respect to s:
Using L{tf(t)} = −F′(s):
We know:
Differentiate:
Therefore:
Hence:
Multiplying f(t) by eat shifts the s-variable.
Therefore:
Use:
Replace a by −a:
Therefore:
Using the standard result:
Here a = 2:
The general result is:
For n = 2:
Since 2! = 2:
Since:
Therefore:
We know:
Here a = 2, so replace s by s−2:
We know:
Apply the exponential shifting property:
Therefore:
Start with:
Since the exponential is e−3t, replace s by s+3:
We know:
Because of e−2t, replace s by s+2:
Since:
Taking inverse Laplace transform:
We know:
Therefore:
We know:
Therefore:
Using:
Therefore:
Comparing with the standard transform pair:
Hence:
We know:
Therefore:
Compare the given expression with the standard transform:
Hence:
Therefore:
Compare the expression:
with the standard Laplace transform of sinh(at).
Compare the given expression with:
Therefore:
🔵 Laplace Transform MCQs
Q51–Q100 • Detailed Solutions
Use partial fractions:
Putting s = 0 gives A = 1.
Putting s = −1 gives B = −1.
Taking inverse Laplace:
Taking inverse Laplace:
Therefore:
Factor the denominator:
Write:
Solving gives A = 1 and B = 1.
Hence:
Taking inverse Laplace:
Compare with:
Here a² = 4, so a = 2.
For a = 2:
Hence the inverse is sin(2t).
Therefore:
Use:
Here a = 3.
Putting a = 3:
Use:
For a = 2:
Use:
For a = 3:
Use:
Here a = −1:
Therefore:
We know:
Apply the shifting rule with s replaced by s+2:
Start with:
Replace s with s+2:
The standard form is:
Comparing:
Therefore:
Use:
Here a = 1 and b = 2.
Compare with:
Here:
Therefore a = −3.
Also b² = 16, so b = 4.
Use:
Here a = −3 and b = 4.
Use:
Comparing:
Thus a = −1.
Also b = 3.
The Laplace transform is linear:
Therefore:
A constant multiplier can be taken outside the Laplace transform:
Thus:
Using the definition:
The entire integrand is zero.
This is one of the fundamental Laplace transform formulas.
For example, n = 3:
Use:
For a = 1:
Put a = 1:
Use:
For a = 1:
For a = 1:
Use:
Here a = −1:
Therefore:
Putting a = 2:
Multiplying by 4:
Use linearity:
Therefore:
Multiply by 3:
Multiply by 5:
Now:
Therefore:
A standard Laplace property states:
This property is useful when the time-domain function is divided by t.
The derivative property converts derivatives in the time domain into algebraic expressions involving s in the Laplace domain.
This conversion makes many differential equations easier to solve algebraically.
Use:
Given:
and f(0)=1.
Substitute:
Use partial fractions:
Solving the coefficients gives:
Therefore:
Taking inverse Laplace:
Complete the square:
Rewrite the numerator:
Therefore:
Now:
Also:
We know:
Let:
Differentiate:
Using L{tf(t)} = −F′(s):
We know:
Differentiate with respect to s:
Hence:
Therefore the correct expression is:
Start with:
Differentiate:
Since:
we get:
First derivative:
Apply the derivative property once more:
Substitute the first derivative result:
Expand:
This formula is especially important when solving second-order differential equations using Laplace transforms.