A signal f(t) has the Laplace transform F(s) = (−8s + 9)/(s² + 13s + 40). Use the initial value theorem to find f(0⁺), the value of f(t) just after t = 0.
Laplace transforms worksheet with answers
A signal f(t) has the Laplace transform F(s) = (−9s + 32)/(s² + 12s + 32). Use the initial value theorem to find f(0⁺), the value of f(t) just after t = 0.
Find f(t) for F(s) = 60/(s(s + 4)(s + 5)) by partial fractions, and evaluate f(0.1).
F(s) = (6s + 40)/(s² + 4s + 3). Its inverse transform has the form f(t) = A·e−t + B·e−3t. Find the coefficient A by partial fractions.
A system obeys y″ + 3y′ + 2y = 8·u(t), with y(0) = 3 and y′(0) = 0. At t = 0 a step input u(t) = 1 is applied. Use the Laplace transform to find y(0.25).
A system is described by the differential equation y″ + 6y′ + 8y = u′ + 10u, 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 = 0.6 s. Find g(0.6).
Answer key
- 1. f(0⁺) = −8
- 2. f(0⁺) = −9
- 3. f(0.1) = 0.2236
- 4. A = 17
- 5. y(0.25) = 3.049
- 6. g(0.6) = 0.9326
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