Final answer:
The magnitude of the friction force exerted by the monkey is 18.0 N.
Step-by-step explanation:
The magnitude of the friction force can be determined using Newton's Second Law in conjunction with the given information. Newton's Second Law states that force is equal to mass multiplied by acceleration (F = m * a). In this case, the horizontal force applied by the monkey is equivalent to the friction force (F = friction force). Therefore, by applying Newton's Second Law, we can solve for the friction force:
F = m * a
F = 18.0 N
F = 18.0 N (friction force)
Therefore, the magnitude of the friction force is 18.0 N.