Chapter 3, Problem 7STP

To determine

The time interval for which the net force on the book is opposite to the motion of the book.

Answer to Problem 7STP

Option (B) is correct.

Explanation of Solution

Introduction:

The slope of the speed-time graph is same as the acceleration of the object and acceleration is the measure of the force on an object. If slope of the speed-time graph is positive, then the motion of the object remains in the direction of the force on the object and motion become opposite to force on decreasing the slope.

The slope of the object in the graph increases for the time interval to So, the net force on the object acts along the motion of the object. The slope starts decreasing from the and decreases up to So, the force on the object for time interval to acts opposite to the motion of the object.

Conclusion:

Thus, the net force on the book for the time interval to acts opposite to the motion of the object.