Engineering Mathematics Miscellaneous


Engineering Mathematics Miscellaneous

Engineering Mathematics

  1. F(s) is the Laplace transform of the function f(t) = 2t²e–t
    F(1) is _______(correct to two decimal places.)









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    Applying Laplace transform

    L[ten] =
    n!
    Sn+1

    L[t²] =
    2

    L[2t²] =
    4

    F(S) = L[e-t.2t²] =
    4
    (S + 1)³

    Putting s = 1 we get
    F(1) =
    4
    =
    4
    = 0.5
    (1 + 1)³8

    Correct Option: B

    Applying Laplace transform

    L[ten] =
    n!
    Sn+1

    L[t²] =
    2

    L[2t²] =
    4

    F(S) = L[e-t.2t²] =
    4
    (S + 1)³

    Putting s = 1 we get
    F(1) =
    4
    =
    4
    = 0.5
    (1 + 1)³8


  1. A parabola x = y² with 0 ≤ x ≤ 1 is shown in the figure. The volume of the solid of rotation obtained by rotating the shaded area by 360° around the x-axis is









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    Here, volume of solid of rotation by rotating shaded area by 360° around x-axis is,
    V = 10πy²dx

    V = 10 πx dx =
    πx²
    ² =
    π
    202

    Correct Option: B


    Here, volume of solid of rotation by rotating shaded area by 360° around x-axis is,
    V = 10πy²dx

    V = 10 πx dx =
    πx²
    ² =
    π
    202



  1. The value of the following definite integral is _____ (round off to there decimal places).
    e1(xInx)dx









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    I = e1x In xdx

    =
    In x²
    - ∫
    1
    ×
    dx
    2x2

    =
    x² In x
    -
    e
    214

    =
    -
    +
    1
    244

    =
    e² + 1
    = 2.097
    4

    Correct Option: C

    I = e1x In xdx

    =
    In x²
    - ∫
    1
    ×
    dx
    2x2

    =
    x² In x
    -
    e
    214

    =
    -
    +
    1
    244

    =
    e² + 1
    = 2.097
    4


  1. Given a vector U =
    1
    (-y³î + x³ĵ + z³̂k)
    3
    and nˆ as the unit normal vector to the surface of the hemisphere (x² + y² + z² = 1; z ≥ 0), the value of integral ∫(∇ × u) nˆ dS evaluated on the curved surface of the hemisphere S is









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    = 0 + 0 + (x² + y²)k̂
    n̂ = k̂
    ∇ × u). n̂ = (∇ × v). k̂ = x² + y²
    ∫∫(x² + y²)dx dy
    010r²(rdrdθ) = π/2

    Correct Option: C


    = 0 + 0 + (x² + y²)k̂
    n̂ = k̂
    ∇ × u). n̂ = (∇ × v). k̂ = x² + y²
    ∫∫(x² + y²)dx dy
    010r²(rdrdθ) = π/2



  1. It is given that y + 2 y' = 0, y = 0, y(0) = 0, y(1)= 0. What is y(0.5)?









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    y" + 2y' + y = 0
    A.E is, D² + 2D + 1 = 0
    ⇒ (D + 1)² = 0
    ⇒ m = – 1
    The C.F. is (C1 + C2 x)e–x and P.I. = 0
    Now y(0) = 0
    ⇒ C1 = 0 a
    nd y(1) = 0
    ⇒ C2 e–1 = 0,
    ⇒ C2 = 0
    ⇒ C.F. = 0
    ⇒ y(0.5) = 0

    Correct Option: A

    y" + 2y' + y = 0
    A.E is, D² + 2D + 1 = 0
    ⇒ (D + 1)² = 0
    ⇒ m = – 1
    The C.F. is (C1 + C2 x)e–x and P.I. = 0
    Now y(0) = 0
    ⇒ C1 = 0 a
    nd y(1) = 0
    ⇒ C2 e–1 = 0,
    ⇒ C2 = 0
    ⇒ C.F. = 0
    ⇒ y(0.5) = 0