A signal f(t) has the Laplace transform F(s) = (−4s + 38)/(s² + 8s + 3). Find the initial slope f′(0⁺) with the initial value theorem.
Laplace transforms worksheet with answers
A signal f(t) has the Laplace transform F(s) = 30/(s(s² + 2s + 25)). Use the final value theorem to find the value f(∞) that f(t) settles to.
Find f(t) for F(s) = 5/(s² + 8s + 32) by completing the square, and evaluate f(0.3).
Find f(t) for F(s) = (4s + 17)/(s² + 4s + 40) by completing the square, and evaluate f(0.6).
A system is described by the differential equation y″ + 4y′ + 29y = 2u′ + 13u, with input u(t) and output y(t). Find its transfer function G(s) = Y(s)/U(s) (zero initial conditions) and evaluate the impulse response g(t) at t = 0.75 s. Find g(0.75).
A system obeys y″ + 7y′ + 10y = 40·u(t), with y(0) = 4 and y′(0) = 0. At t = 0 a step input u(t) = 1 is applied. Use the Laplace transform to find y(0.5).
Answer key
- 1. f′(0⁺) = 70
- 2. f(∞) = 1.2
- 3. f(0.3) = 0.3509
- 4. f(0.6) = −1.28
- 5. g(0.75) = −0.5957
- 6. y(0.5) = 4
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