A vector field (mathbf{F}) and contour lines of a potential function for (mathbf{F}) are shown in Figure

Question:

A vector field $\mathbf{F}$ and contour lines of a potential function for $\mathbf{F}$ are shown in Figure 17. Calculate the common value of $\int_{C} \mathbf{F} \cdot d \mathbf{r}$ for the curves shown in Figure 17 oriented in the direction from $P$ to $Q$.