Final answer:
The net force on the box when pushed by two forces in opposite directions is found by subtracting the smaller force from the larger force, resulting in a net force of 9 N to the right.
Step-by-step explanation:
When David pushes a box with a force of 14 Newtons to the right, and his friend pushes the same box with a force of 5 Newtons to the left, we need to find the net force acting on the box. To calculate the net force, we subtract the smaller force from the larger force and keep the direction of the larger force. Thus, the net force would be 14 N (to the right) - 5 N (to the left) = 9 N to the right. Therefore, the net force acting on the box is 9 N to the right, which corresponds to option b) 9 N to the right.