Considering the sign of work allows for the differentiation between forces contributing to motion (positive work) and forces opposing motion (negative work), providing a comprehensive understanding of energy transfer in various physical situations.

In this scenario, the work done is calculated as the negative product of the force and displacement, signifying the reduction in energy or the opposition to the motion of the object.

When a retarding force is applied opposite to the direction of motion, the angle between the force and displacement is 180 degrees, resulting in negative work done.

When the force and displacement are parallel, the work done is positive because the force contributes to the motion of the object in the direction of displacement.

In this scenario, the work done is calculated as the product of the force exerted by the baby and the displacement of the toy car, with the work considered positive due to the alignment of force and displacement.