A mass of 10 kg is at a point A on a table. It is moved to a point B. If the line joining A and B is horizontal, what is the work done on the object by the gravitational force? Explain your answer.
Explanation The gravitational forced always acts vertically downward and the object will move in a horizontal direction from A to B. Workdone is the product of force and displacement, but the direction of displacement acts in the direction of force. But in this case the object move horizontally in the table and gravitational force acts vertically downward i.e. Force and displacement are perpendicular direction. The workdone on the object by the gravitational force is zero.
