Please solve d and e only solution of a,b,c is provided

Calculus For The Life Sciences
2nd Edition
ISBN:9780321964038
Author:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Chapter11: Differential Equations
Section11.1: Solutions Of Elementary And Separable Differential Equations
Problem 18E: Find the general solution for each differential equation. Verify that each solution satisfies the...
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Please solve d and e only solution of a,b,c is provided 

Case(A) We have to find out the particular
function of the form
⇒ xp = A cos(45t) + B sin(45t)
d
Now xp
& xp
=
dt
= -45A sin(45t) + 45B cos(45t)
d
[-45A sin(45t) + 45B cos(45t)]
dt
= -2025A cos(45t) - 2025B sin(45t)
=
[A cos(45t) + B sin(45t)]
Since xp will satisfy eqn(3) so we get,
→ [-2025A cos(45t) - 2025B sin(45t)]
+3025[A cos(45t) + B sin(45t)] = 500 cos(45t)
⇒ 1000A cos(45t) + 1000B sin(45t) = 500 cos(45t)
On comparison, we get
⇒ 1000A = 500 & 1000B = 0
1
⇒ A=
2
So required particular solution is given by
1
⇒ xp = cos(45t)
2
& B = 0
Case(B) General solution of eqn(3) is given by
⇒x=Xc + Xp
1
⇒ x = C₁ Cos(55t) + C₂ sin(55t) += cos(45t)
2
Case(C) We have x(0) = 0 so from eqn(4),
1
⇒0=C₁ +0+ ⇒C1=-
2
Then eqn(4) reduces into
1
2
Now x' =
⇒x'=
1
⇒X=-- cos(55t) + C₂ sin(55t) + -cos(45t)
2
d
dt
55
2
1
2
1
cos(55t) + C2 sin(55t) + -cos(45t)
2
45
-sin(55t) +55c2 cos(55t) -—=sin(45t)
2
We have given that, x'(0) = 0 so from eqn(6)
⇒ 0 = 0+55c₂-0 C₂ = 0
Therefore required solution is given by,
1
1
⇒X=-- cos(55t) + cos(45t)
2
2
(4)
(5)
(6)
Transcribed Image Text:Case(A) We have to find out the particular function of the form ⇒ xp = A cos(45t) + B sin(45t) d Now xp & xp = dt = -45A sin(45t) + 45B cos(45t) d [-45A sin(45t) + 45B cos(45t)] dt = -2025A cos(45t) - 2025B sin(45t) = [A cos(45t) + B sin(45t)] Since xp will satisfy eqn(3) so we get, → [-2025A cos(45t) - 2025B sin(45t)] +3025[A cos(45t) + B sin(45t)] = 500 cos(45t) ⇒ 1000A cos(45t) + 1000B sin(45t) = 500 cos(45t) On comparison, we get ⇒ 1000A = 500 & 1000B = 0 1 ⇒ A= 2 So required particular solution is given by 1 ⇒ xp = cos(45t) 2 & B = 0 Case(B) General solution of eqn(3) is given by ⇒x=Xc + Xp 1 ⇒ x = C₁ Cos(55t) + C₂ sin(55t) += cos(45t) 2 Case(C) We have x(0) = 0 so from eqn(4), 1 ⇒0=C₁ +0+ ⇒C1=- 2 Then eqn(4) reduces into 1 2 Now x' = ⇒x'= 1 ⇒X=-- cos(55t) + C₂ sin(55t) + -cos(45t) 2 d dt 55 2 1 2 1 cos(55t) + C2 sin(55t) + -cos(45t) 2 45 -sin(55t) +55c2 cos(55t) -—=sin(45t) 2 We have given that, x'(0) = 0 so from eqn(6) ⇒ 0 = 0+55c₂-0 C₂ = 0 Therefore required solution is given by, 1 1 ⇒X=-- cos(55t) + cos(45t) 2 2 (4) (5) (6)
3025,
6. Beats. Consider a free undamped oscillator with mass m = 1 and stiffness k =
which satisfies the differential equation
x"(t) + 3025x(t) = 0.
The natural frequency is wo
√k/m = 55 and the general solution is e(t) = C₁ cos(55t) +
C₂ sin(55t). Now suppose we subject this oscillator to a periodic external force with amplitude
500 and frequency 45:
x"(t) + 3025x(t)
500 cos(45t).
(a) Find a particular solution of the form xp(t) = A cos(45t) + B sin(45t).
(b) Find the general solution r(t) = xc(t) + xp(t).
(c) Find the unique solution r(t) with initial conditions (0) = 0 and x'(0) = 0.
(d) Express your solution in the form x(t) = C sin(at) sin(ßt). [Hint: Use the trig identities
-
cos(a - b) = cos a cos 3 + sin a sin 3,
cos(a + B) = cos a cos - sin a sin 3,
cos(a + 3) = 2 sin a sin 6.]
cos(a - b)
(e) Plot your solution r(t) for t between 0 and 3π/5. [Use a computer.]
Transcribed Image Text:3025, 6. Beats. Consider a free undamped oscillator with mass m = 1 and stiffness k = which satisfies the differential equation x"(t) + 3025x(t) = 0. The natural frequency is wo √k/m = 55 and the general solution is e(t) = C₁ cos(55t) + C₂ sin(55t). Now suppose we subject this oscillator to a periodic external force with amplitude 500 and frequency 45: x"(t) + 3025x(t) 500 cos(45t). (a) Find a particular solution of the form xp(t) = A cos(45t) + B sin(45t). (b) Find the general solution r(t) = xc(t) + xp(t). (c) Find the unique solution r(t) with initial conditions (0) = 0 and x'(0) = 0. (d) Express your solution in the form x(t) = C sin(at) sin(ßt). [Hint: Use the trig identities - cos(a - b) = cos a cos 3 + sin a sin 3, cos(a + B) = cos a cos - sin a sin 3, cos(a + 3) = 2 sin a sin 6.] cos(a - b) (e) Plot your solution r(t) for t between 0 and 3π/5. [Use a computer.]
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