In the previous section, we looked into the definition of work. In this section, we are going to see
- Whether force is unidirectional or not.
- Whether work done by a force is positive or negative.
Consider the case in which the force and the displacement are in the same direction:
- A girl pulls a toy car that is parallel to the ground, as shown in figure.
- The baby applies a force in the direction of displacement of the vehicle.
In these cases, the work done will be equal to the product of the force and displacement.
In such cases, the work done by the force is taken as positive.
Consider the scenario in which an object moves with a uniform velocity along a particular direction.
Retarding force, \(F\), is applied in the opposite direction to the object's movement. That is, the angle between the two directions is \(180º\). Let the object stops after a displacement \(s\).
In such cases, the work done by the force, \(F\), is taken as negative and denoted by the minus sign.
From the above discussion, the work done by a force can be either positive or negative.