A)
Upward force = Normal Force
Downward force = weight
Resultant force = ma
Resultant = Weight - Normal
1.2 x 5 = 1.2 x 9.81 - Fn
Fn = 5.77 N
B)
The reactant force is equal to the force exerted by the dog, just in the opposite direction. Thus, the dog's force is also 5.77 N.