A quantity grows according to dy/dt = k·y with k > 0. It is 120 at t = 0 and 300 at t = 4 h. Find the rate constant k in h⁻¹.
Differential equations worksheet with answers
1.Easy
y(0) = 120y(4) = 300
k = h⁻¹
2.Easy
For the equation y″ + 7y′ + 12y = 0, find the root r of the characteristic equation that is closest to zero. It sets how slowly the solution dies out.
y″ + 7y′ + 12y = 0
r =
3.Medium
Solve y″ + 8y′ + 16y = 0 with y(0) = 1 and y′(0) = 1. Find y(1.5).
y″ + 8y′ + 16y = 0y(0) = 1y′(0) = 1
y(1.5) =
4.Medium
Solve y″ + 2y′ + y = 0 with y(0) = 1 and y′(0) = 1. Find y(1.5).
y″ + 2y′ + y = 0y(0) = 1y′(0) = 1
y(1.5) =
5.Hard
Solve the initial value problem y′ + y/x = x for x > 0, with y(1) = 0. Find y(3).
y′ + y/x = xy(1) = 0
y(3) =
6.Hard
Solve y″ + 4y′ + 29y = 0 with y(0) = 5 and y′(0) = 0 (released from rest). Find y(1); angles in radians.
y″ + 4y′ + 29y = 0y(0) = 5y′(0) = 0
y(1) =
Answer key
- 1. k = 0.2291 h⁻¹
- 2. r = −3
- 3. y(1.5) = 0.02107
- 4. y(1.5) = 0.8925
- 5. y(3) = 2.889
- 6. y(1) = −0.06761
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