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 work done on the object by the gravitational force is zero. This is because the motion of object is in the

horizontal direction whereas the gravitational force (acting vertically downwards) is at right angles (`90^(@)` angle) to the direction of motion of object. `W = F cos 90^(@) xx s = F xx 0 xx s = 0` (because `cos 90^(@) = 0`)