A signal f(t) has the Laplace transform F(s) = (−3s + 15)/(s² + 4s + 17). Find the initial slope f′(0⁺) with the initial value theorem.
Laplace transforms worksheet with answers
1.Easy
F(s) = (−3s + 15)/(s² + 4s + 17)
f′(0⁺) =
2.Easy
A signal f(t) has the Laplace transform F(s) = (7s + 27)/(s² + 4s + 14). Find the initial slope f′(0⁺) with the initial value theorem.
F(s) = (7s + 27)/(s² + 4s + 14)
f′(0⁺) =
3.Medium
Find f(t) for F(s) = 60/(s(s + 1)(s + 4)) by partial fractions, and evaluate f(1).
F(s) = 60/(s(s + 1)(s + 4))t = 1 s
f(1) =
4.Medium
Find f(t) for F(s) = 22/(s² + 4s + 40) by completing the square, and evaluate f(0.3).
F(s) = 22/(s² + 4s + 40)t = 0.3 s
f(0.3) =
5.Hard
A system obeys y″ + 7y′ + 10y = 40·u(t), with y(0) = 1 and y′(0) = 0. At t = 0 a step input u(t) = 10 is applied. Use the Laplace transform to find y(0.4).
y″ + 7y′ + 10y = 40·u(t)y(0) = 1y′(0) = 0u(t) = 10t = 0.4 s
y(0.4) =
6.Hard
A system obeys y″ + 3y′ + 2y = 2·u(t), with y(0) = 4 and y′(0) = 0. At t = 0 a step input u(t) = 2 is applied. Use the Laplace transform to find y(0.5).
y″ + 3y′ + 2y = 2·u(t)y(0) = 4y′(0) = 0u(t) = 2t = 0.5 s
y(0.5) =
Answer key
- 1. f′(0⁺) = 27
- 2. f′(0⁺) = −1
- 3. f(1) = 7.734
- 4. f(0.3) = 1.96
- 5. y(0.4) = 14.31
- 6. y(0.5) = 3.69
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