A quantity grows according to dy/dt = k·y with k > 0. It is 400 at t = 0 and 1560 at t = 11 h. Find the rate constant k in h⁻¹.
Differential equations worksheet with answers
1.Easy
y(0) = 400y(11) = 1560
k = h⁻¹
2.Easy
A mass–spring–damper is described by y″ + 6y′ + 25y = 0. Compare it with y″ + 2ζωny′ + ωn²y = 0 and find the damping ratio ζ.
y″ + 6y′ + 25y = 0
ζ =
3.Medium
Solve y″ + 4y′ + 4y = 0 with y(0) = 5 and y′(0) = 4. Find y(1).
y″ + 4y′ + 4y = 0y(0) = 5y′(0) = 4
y(1) =
4.Medium
Solve y″ + 7y′ + 12y = 0 with y(0) = 1 and y′(0) = 6. Find y(1.5).
y″ + 7y′ + 12y = 0y(0) = 1y′(0) = 6
y(1.5) =
5.Hard
Solve y′ + y = 4e−3t with y(0) = 5. Find y(0.5).
y′ + y = 4e−3ty(0) = 5
y(0.5) =
6.Hard
A system obeys y″ + 4y′ + 29y = 145 for t ≥ 0, starting from rest: y(0) = 0, y′(0) = 0. Find the peak value ymax of its step response.
y″ + 4y′ + 29y = 145y(0) = 0y′(0) = 0
ymax =
Answer key
- 1. k = 0.1237 h⁻¹
- 2. ζ = 0.6
- 3. y(1) = 2.571
- 4. y(1.5) = 0.08878
- 5. y(0.5) = 3.799
- 6. ymax = 6.423
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