Week 9

Week 9

Tutorial 9: Laplace Transform 2



  1. Evaluate the given Laplace transform. i.
    1. ii.
      iii.
      iv.
      v.
      vi.
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      Solution
      Question (i)
      Question (ii)
      Question (iii)
      Question (iv)
      Question (v)
      Question (vi)
  1. Use the Laplace transform to solve the initial-value problem.
    1. i.
      ii. where
      iii.
      iv.
      v.
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      Solution
      Question (i)
      Let
      Question (ii)
      The Laplace transform of the differential equation is
      Question (iii)
      The Laplace transform of the differential equation is
      Question (iv)
      The Laplace transform of the differential equation is
      Let
      Let
      Question (v)
  1. Use the Laplace transform to solve the given system of differential equations.
    1. i.
      ii.
      iii.
      👉
      Solution
      Question (i)
      From , and subsitute into
      By partial fraction,
      Therefore,
      Question (ii)
      Let
      By partial fraction,
      Therefore,
      Question (iii)
      Then,
  1. Two masses and are connected to three springs of negligible mass having spring constants and , respectively.
    1. notion image
      Let and represent displacements of masses and from their equilibrium positions. The motion of the coupled system is represented by the system of second-order differential equations:
      Using Laplace transform to solve the system when and .
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      Solution
      For
      Substitute unknowns:
      Laplace transform:
      For
      Substitute unknowns:
      Laplace transform:
      Hence,
      From
      Substitute into
      Substitute into
      Inverse Laplace,
  1. The system of differential equations for the charge on the capacitor and the current in the electrical network shown below is
    1. notion image
      Find the charge on the capacitor using Laplace transform when .
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      Solution
      Solving and :