Final answer:
The net force on the top box can be found by subtracting the force of friction between the boxes from the applied force. The force of friction can be calculated using the coefficient of friction and the weight of the boxes. Once you have the force of friction, you can subtract it from the applied force to find the net force on the top box.
Step-by-step explanation:
When a 15.0-N pull to the right is exerted on the lower box, both boxes move together. Since the two boxes are in contact with each other and moving together, they experience the same acceleration. The net force on the top box can be found by subtracting the force of friction between the boxes from the applied force:
Net force on the top box = Applied force - Force of friction
The force of friction can be found using the formula:
Force of friction = Coefficient of friction * Normal force
Since the boxes are on a smooth horizontal floor, there is no normal force between the top box and the floor. Therefore, the normal force on the top box is equal to its weight:
Normal force = Weight = mass * acceleration due to gravity
Substituting the values into the formula, we get:
Force of friction = Coefficient of friction * (Weight of top box + Weight of lower box)
Finally, we can substitute the values of the forces and solve for the net force on the top box.