Now, imagine that you are helping a library move. You are lifting boxes of books onto a cart. Most of the boxes are full of many books, but one of the boxes was closed, only having a few books in it. You go to lift this box, not knowing it has less mass, with the same amount of force as you used to lift the full boxes. How will the acceleration of this box compare to the acceleration of a full box? Newton’s second law of motion tells us that if the force remains constant and the mass is decreased, the object will accelerate at a faster rate. Because the acceleration increases when the mass decreases, we say that acceleration is inversely proportional to mass. Give an example of a situation where you might use the mathematical formula for Newton's second law to solve a problem. Explain how the formula would be useful in this situation.