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A function n(x) satisfies the differential equation $$\frac{{{{\text{d}}^2}{\text{n}}\left( {\text{x}} \right)}}{{{\text{d}}{{\text{x}}^2}}} - \frac{{{\text{n}}\left( {\text{x}} \right)}}{{{{\text{L}}^2}}} = 0$$ where L is a constant. The boundary conditions are: n(0) = K and n($$\infty $$) = 0. The solution to this equation is
A
n(x) = K exp(x/L)
B
n(x)= K exp(-x/√L)
C
n(x) = K<sup>2</sup> exp(-x/L)
D
n(x) = K exp(-x/L)
Correct Answer:
n(x) = K exp(-x/L)
The figure shows the plot of y as a function of x
The function shown is the solution of the differential equation (assuming all initial conditions to be zero) is
A
$$\frac{{{{\text{d}}^2}{\text{y}}}}{{{\text{d}}{{\text{x}}^2}}} = 1$$
B
$$\frac{{{\text{dy}}}}{{{\text{dx}}}} = {\text{x}}$$
C
$$\frac{{{\text{dy}}}}{{{\text{dx}}}} = - {\text{x}}$$
D
$$\frac{{{\text{dy}}}}{{{\text{dx}}}} = \left| {\text{x}} \right|$$
Solution of a differential equation is any function which satisfies the equation.
A
False
B
True
The solution to the differential equation $$\frac{{{{\text{d}}^2} \cdot {\text{u}}}}{{{\text{d}}{{\text{x}}^2}}} - {\text{k}}\frac{{{\text{du}}}}{{{\text{dx}}}} = 0$$ is where k is constant, subjected to the boundary conditions u(0) = 0 and u(L) = U, is
A
$${\text{u}} = {\text{U}}\frac{{\text{x}}}{{\text{L}}}$$
B
$${\text{u}} = {\text{U}}\left( {\frac{{1 - {{\text{e}}^{{\text{kx}}}}}}{{1 - {{\text{e}}^{{\text{kL}}}}}}} \right)$$
C
$${\text{u}} = {\text{U}}\left( {\frac{{1 - {{\text{e}}^{ - {\text{kx}}}}}}{{1 - {{\text{e}}^{ - {\text{kL}}}}}}} \right)$$
D
$${\text{u}} = {\text{U}}\left( {\frac{{1 + {{\text{e}}^{{\text{kx}}}}}}{{1 + {{\text{e}}^{{\text{kL}}}}}}} \right)$$
The solution of differential equation $$\frac{{{{\text{d}}^2}{\text{u}}}}{{{\text{d}}{{\text{x}}^2}}} - {\text{K}}\frac{{{\text{du}}}}{{{\text{dx}}}} = 0$$ where K is constant, subjected to boundary conditions u(0) = 0 and u(L) = U is
A
$${\text{u}} = \frac{{{\text{Ux}}}}{{\text{L}}}$$
B
$${\text{u}} = {\text{U}}\left$$
C
$${\text{u}} = {\text{U}}\left$$
D
$${\text{u}} = {\text{U}}\left$$
Singular solution of a differential equation is one that cannot be obtained from the general solution gotten by the usual method of solving the differential equation.
A
True
B
False
A differential equation is given as
$${{\text{x}}^2}\frac{{{{\text{d}}^2}{\text{y}}}}{{{\text{d}}{{\text{x}}^2}}} - 2{\text{x}}\frac{{{\text{dy}}}}{{{\text{dx}}}} + 2{\text{y}} = 4$$
The solution of differential equation in terms of arbitrary constant C
1
and C
2
is
A
$${\text{y}} = \frac{{{{\text{C}}_1}}}{{{{\text{x}}^2}}} + {{\text{C}}_2}{\text{x}} + 2$$
B
$${\text{y}} = {{\text{C}}_1}{{\text{x}}^2} + {{\text{C}}_2}{\text{x}} + 4$$
C
$${\text{y}} = {{\text{C}}_1}{{\text{x}}^2} + {{\text{C}}_2}{\text{x}} + 2$$
D
$${\text{y}} = \frac{{{{\text{C}}_1}}}{{{{\text{x}}^2}}} + {{\text{C}}_2}{\text{x}} + 2$$
The function f(t) satisfies the differential equation $$\frac{{{{\text{d}}^2}{\text{f}}}}{{{\text{d}}{{\text{t}}^2}}} + {\text{f}} = 0$$ and the auxiliary conditions, f(0) = 0, $$\frac{{{\text{df}}}}{{{\text{dt}}}}\left( 0 \right) = 4.$$ The Laplace transform of f(t) is given by
A
$$\frac{2}{{{\text{s}} + 1}}$$
B
$$\frac{4}{{{\text{s}} + 1}}$$
C
$$\frac{4}{{{{\text{s}}^2} + 1}}$$
D
$$\frac{2}{{{{\text{s}}^2} + 1}}$$
In Finite Element Methods (FEM), a boundary value problem is a set of differential equations with a solution, which also satisfies some additional constraints, known as ___
A
boundary conditions
B
nodal values
C
equilibrium equations
D
energy minimum
The nature of normal grain growth in the presence of a second phase deserves special consideration. The moving boundaries will be attached to the particles exert a pulling force on the boundary restricting its motion. Therefore if the boundary intersects the particle surface at 90° the particle will feel a pull of (2πrγcosΘ)*sinΘ. This will be counterbalanced by an equal and opposite force acting on the boundary. As the boundary moves over the particle surface Θ changes and the drag reaches a maximum value, this happens when Θ becomes______
A
90
B
45
C
60
D
30
The boundary layer thickness at a distance of l m from the leading edge of a flat plate, kept at zero angle of incidence to the flow direction, is O.l cm. The velocity outside the boundary layer is 25 ml sec. The boundary layer thickness at a distance of 4 m is (Assume that boundary layer is entirely laminar)
A
0.40 cm
B
0.20 cm
C
0.10 cm
D
0.05 cm