A quantity grows according to dy/dt = k·y with k > 0. It is 200 at t = 0 and 620 at t = 7 h. Find the rate constant k in h⁻¹.
Differential equations worksheet with answers
1.Easy
y(0) = 200y(7) = 620
k = h⁻¹
2.Easy
A quantity grows according to dy/dt = k·y with k > 0. It is 120 at t = 0 and 300 at t = 7 h. Find the rate constant k in h⁻¹.
y(0) = 120y(7) = 300
k = h⁻¹
3.Medium
Solve y″ + 5y′ + 6y = 0 with y(0) = 2 and y′(0) = 2. Find y(2).
y″ + 5y′ + 6y = 0y(0) = 2y′(0) = 2
y(2) =
4.Medium
A can of soda at 3 °C is taken out of the fridge into a room at 22 °C. After 13 min its temperature is 17 °C. It follows Newton's law of cooling, dT/dt = −k·(T − Tₐ). Find the constant k in min⁻¹.
T0 = 3 °CTa = 22 °CT(13) = 17 °C
k = min⁻¹
5.Hard
A system obeys y″ + 2y′ + 17y = 17 for t ≥ 0, starting from rest: y(0) = 0, y′(0) = 0. Find y(0.5); angles in radians.
y″ + 2y′ + 17y = 17y(0) = 0y′(0) = 0
y(0.5) =
6.Hard
Solve y′ + 0.5y = 4e−2t with y(0) = 0. Find y(1).
y′ + 0.5y = 4e−2ty(0) = 0
y(1) =
Answer key
- 1. k = 0.1616 h⁻¹
- 2. k = 0.1309 h⁻¹
- 3. y(2) = 0.1317
- 4. k = 0.1027 min⁻¹
- 5. y(0.5) = 1.115
- 6. y(1) = 1.257
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