Final answer:
The net force on the block is the frictional force, which is calculated as the product of the coefficient of friction (0.20) and the normal force (40 N), resulting in 8 N to the left.
Step-by-step explanation:
The question asks for the net force on a sliding block on a horizontal surface, considering various forces such as gravitational force, normal force, and frictional force. Given that the gravitational force and the normal force are equal in magnitude and opposite in direction, they cancel each other out. The frictional force can be calculated using the coefficient of friction (µ) and the normal force (N), with the formula Ffriction = µN. Since µ is 0.20 and N is 40 N, the frictional force is Ffriction = 0.20 × 40 N = 8 N to the left. If there are no other horizontal forces acting on the block, the net force on the block is 8 N to the left, which correlates with the direction of the frictional force.