Heya!!
For calculate aceleration, lets applicate second law of Newton:

Δ Being Δ
F = Force = 4 N
m = mass = 36 kg
a = Aceleration = ?
⇒ Let's replace according the formula:

⇒ Clear acceleration and resolve it:

Result:
The aceleration is of 0,111 meters per second squared (m/s²)
Good Luck!!