A mass–spring–damper is described by y″ + 3.2y′ + 4y = 0. Compare it with y″ + 2ζωny′ + ωn²y = 0 and find the damping ratio ζ.
Differential equations worksheet with answers
1.Easy
y″ + 3.2y′ + 4y = 0
ζ =
2.Easy
A mass–spring–damper is described by y″ + 3y′ + 9y = 0. Compare it with y″ + 2ζωny′ + ωn²y = 0 and find the damping ratio ζ.
y″ + 3y′ + 9y = 0
ζ =
3.Medium
A cup of coffee at 88 °C is left in a room at 22 °C. It follows Newton's law of cooling, dT/dt = −k·(T − Tₐ). With k = 0.11 min⁻¹, find its temperature T after 25 min.
T0 = 88 °CTa = 22 °Ck = 0.11 min⁻¹t = 25 min
T = °C
4.Medium
Solve y″ + 7y′ + 12y = 0 with y(0) = 4 and y′(0) = 0. Find y(1).
y″ + 7y′ + 12y = 0y(0) = 4y′(0) = 0
y(1) =
5.Hard
Solve y′ + 2y = 9e−t with y(0) = 5. Find y(1).
y′ + 2y = 9e−ty(0) = 5
y(1) =
6.Hard
A system obeys y″ + 4y′ + 29y = 29 for t ≥ 0, starting from rest: y(0) = 0, y′(0) = 0. Find y(1); angles in radians.
y″ + 4y′ + 29y = 29y(0) = 0y′(0) = 0
y(1) =
Answer key
- 1. ζ = 0.8
- 2. ζ = 0.5
- 3. T = 26.22 °C
- 4. y(1) = 0.5768
- 5. y(1) = 2.77
- 6. y(1) = 1.014
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