A mass–spring–damper is described by y″ + 18y′ + 36y = 0. Compare it with y″ + 2ζωny′ + ωn²y = 0 and find the damping ratio ζ.
Differential equations worksheet with answers
1.Easy
y″ + 18y′ + 36y = 0
ζ =
2.Easy
For the equation y″ + 4y′ + 3y = 0, find the root r of the characteristic equation that is closest to zero. It sets how slowly the solution dies out.
y″ + 4y′ + 3y = 0
r =
3.Medium
Solve y″ + 4y′ + 4y = 0 with y(0) = 2 and y′(0) = 4. Find y(1.5).
y″ + 4y′ + 4y = 0y(0) = 2y′(0) = 4
y(1.5) =
4.Medium
Solve y″ + 4y′ + 4y = 0 with y(0) = 3 and y′(0) = 2. Find y(1.5).
y″ + 4y′ + 4y = 0y(0) = 3y′(0) = 2
y(1.5) =
5.Hard
Solve y′ + 3y = 6e−0.5t with y(0) = 1. Find y(0.5).
y′ + 3y = 6e−0.5ty(0) = 1
y(0.5) =
6.Hard
A system obeys y″ + y′ + 4.25y = 42.5 for t ≥ 0, starting from rest: y(0) = 0, y′(0) = 0. Find y(1.5); angles in radians.
y″ + y′ + 4.25y = 42.5y(0) = 0y′(0) = 0
y(1.5) =
Answer key
- 1. ζ = 1.5
- 2. r = −1
- 3. y(1.5) = 0.697
- 4. y(1.5) = 0.7468
- 5. y(0.5) = 1.557
- 6. y(1.5) = 14.51
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