A quantity grows according to dy/dt = k·y with k > 0. It is 100 at t = 0 and 290 at t = 11 h. Find the rate constant k in h⁻¹.
Differential equations worksheet with answers
A mass–spring–damper is described by y″ + 1.6y′ + 4y = 0. Compare it with y″ + 2ζωny′ + ωn²y = 0 and find the damping ratio ζ.
A forged steel part at 440 °C is left to cool in a workshop at 27 °C. After 34 min its temperature is 176 °C. It follows Newton's law of cooling, dT/dt = −k·(T − Tₐ). Find the constant k in min⁻¹.
A forged steel part at 460 °C is left to cool in a workshop at 28 °C. After 40 min its temperature is 86 °C. It follows Newton's law of cooling, dT/dt = −k·(T − Tₐ). Find the constant k in min⁻¹.
Solve the initial value problem y′ + 3y/x = 6 for x > 0, with y(1) = 5. Find y(3).
A system obeys y″ + 4y′ + 20y = 40 for t ≥ 0, starting from rest: y(0) = 0, y′(0) = 0. Find the peak value ymax of its step response.
Answer key
- 1. k = 0.09679 h⁻¹
- 2. ζ = 0.4
- 3. k = 0.02999 min⁻¹
- 4. k = 0.0502 min⁻¹
- 5. y(3) = 4.63
- 6. ymax = 2.416
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