asked 130k views
2 votes
Given that v(0)=5 and v′(0)=10. Solve for V(s) in standard form, manually, on a separate sheet of paper. V( s)=dv2/dt2(t)+5dv(t)/dt+6v(t)=10e−tu(t)

5s240s+45 / s3+6s2+11s+6

1 Answer

4 votes

Answer:

To solve for V(s) in standard form for the given initial value problem, we'll take the Laplace transform of the differential equation. The Laplace transform of a derivative is given by:

L{d^n/dt^n[f(t)]} = s^nF(s) - s^(n-1)f(0) - s^(n-2)f'(0) - ... - f^(n-1)(0)

Where F(s) is the Laplace transform of f(t), and f(0), f'(0), etc., are the initial values of the function and its derivatives.

Given that v(0) = 5 and v'(0) = 10, we have:

v(0) = 5

v'(0) = 10

Now, let's take the Laplace transform of the differential equation:

V(s) = s^2V(s) - s*v(0) - v'(0) + 5sV(s) + 6V(s)

We also have the Laplace transform of the right-hand side:

L{10e^(-t)u(t)} = 10 / (s + 1)

Now, plug in the initial conditions:

V(s) = s^2V(s) - s*5 - 10 + 5sV(s) + 6V(s)

Next, group like terms:

V(s)[s^2 + 5s + 6] = 5s - 10 + 10 / (s + 1)

Now, solve for V(s):

V(s) = [5s - 10 + 10 / (s + 1)] / [s^2 + 5s + 6]

The denominator can be factored:

V(s) = [5s - 10 + 10 / (s + 1)] / [(s + 2)(s + 3)]

Now, we can use partial fraction decomposition to express V(s) in standard form:

V(s) = A/(s + 2) + B/(s + 3) + C/(s + 1)

Multiply both sides by the denominator:

5s - 10 + 10 / (s + 1) = A(s + 3)(s + 1) + B(s + 2)(s + 1) + C(s + 2)(s + 3)

Now, we'll find the values of A, B, and C by equating coefficients of like powers of s on both sides of the equation.

1. Equate the constant terms:

-10 = 3A(1)2 + 2B(1)3 + 2C(3)1

Simplify:

-10 = 3A + 2B + 6C

2. Equate the coefficient of s^1 terms:

5 = 3A(1) + 2B(1) + 2C(1)

Simplify:

5 = 3A + 2B + 2C

3. Equate the coefficient of s^2 terms:

0 = A(1)(3) + B(1)(2) + C(3)(2)

Simplify:

0 = 3A + 2B + 6C

Now, you have a system of three equations with three unknowns:

-10 = 3A + 2B + 6C

5 = 3A + 2B + 2C

0 = 3A + 2B + 6C

You can solve this system of equations to find the values of A, B, and C. Once you have those values, you can express V(s) in standard form.

Explanation:

answered
User Kevinskio
by
8.4k points
Welcome to Qamnty — a place to ask, share, and grow together. Join our community and get real answers from real people.