How can we calculate the work done by a constant force that is not in the direction of the object’s motion? As an example, in Figure 6-6a a groundskeeper is using a rope to pull a screen across a baseball diamond to smooth out the dirt. The net tension force \(\vec{F}\) that the rope exerts on the screen is at an angle with respect to the direction in which the screen moves. In such a case, only the component of the force along the direction of motion contributes to the work done (Figure 6-6b).
If \(\theta\) is the angle between the force \(\vec{F}\) and the displacement \(\vec{d}\), this component of the force is \(F \cos \theta\). Hence the amount of work done by the force is: