Given:
- Number of oscillations per minute = 40
- Maximum speed = 36 cm/s

To find:
- Amplitude of the body's motion

Formula:
The formula to calculate the amplitude of an oscillating body is:
Amplitude (A) = Maximum speed (V_max) / Angular frequency (ω)

The angular frequency (ω) can be calculated as:
Angular frequency (ω) = 2π × Frequency (f)

Frequency (f) can be calculated as:
Frequency (f) = Number of oscillations (n) / Time

Solution:

1. Convert the given number of oscillations per minute to oscillations per second:
Number of oscillations per second = 40 / 60 = 2/3 oscillations per second

2. Calculate the time taken for one oscillation:
Time = 1 / Number of oscillations per second = 1 / (2/3) = 3/2 seconds

3. Calculate the frequency:
Frequency (f) = 1 / Time = 1 / (3/2) = 2/3 Hz

4. Calculate the angular frequency:
Angular frequency (ω) = 2π × Frequency (f) = 2π × (2/3) = 4π/3 rad/s

5. Calculate the amplitude:
Amplitude (A) = Maximum speed (V_max) / Angular frequency (ω) = 36 cm/s / (4π/3 rad/s)

6. Simplify the expression:
Amplitude (A) = 36 cm/s × 3 / (4π) = 27 / π cm ≈ 8.59 cm

Answer:
The amplitude of the body's motion is approximately 8.59 cm.