Answer: 
Explanation:
The acceleration of an object can be calculated by using Newton's second law:

where
F is the net force applied on the object
m is the mass of the object
a is its acceleration
In this problem, we have F=125 N and m=25.0 kg, so we can rearrange the equation to calculate the acceleration:

Mass is the amount of matter in an object. it is measured in grams, kg, ect.
Answer:
The net force is 392N, pointing down.
Explanation:
The net force is the sum of all forces acting on the rock, namely the gravity ("+" acting downward) and the friction force due to air resistance ("-" acting upward):

The net force is 392N and pointing down (positive)/