A scale will read a force value that is equal to the normal force exerted by the scale upon the object that is in contact with its top surface. By analyzing all the other forces that act upon that object, it is possible to predict a value for the scale reading.

The more difficult questions in this Concept Builder include a variety of distracting elements. The trick is to use the same type of analytical and principled-thinking that you used on the easier questions.

Here the 5.0-kg box is at rest, but wedged between two objects - a finger on the bottom side and a scale on its top side. You want to know how the scale reading - that is, the normal force acting between the box and the scale - compares to the weight of the 5.0-kg box. To do so, consider the forces acting upon the box. 

There are two contact forces - the normal force (downwards) from the scale and the pushing force (upwards) from the finger. And then there is force of gravity (the Earth pulling the box downard). These three forces must balance each other. The two down forces - the box weight and the normal force must balance the one up force. But in this case there is no information about the size of the upward force of the finger. And since the normal force and the gravity force are directed in the same direction there is no way to make a comparison of their relative magnitude. So from this type of analysis or reasoning, you should be able to answer the question.