Final answer:
When plotting P vs V in physics, the line is a straight line that shows a direct proportionality between pressure and volume.
Step-by-step explanation:
In physics, when plotting P vs V, the line is a straight line.
This means that P (pressure) is directly proportional to V (volume). As the volume increases, the pressure also increases, and vice versa.
For example, let's say we have a container with gas inside. If we decrease the volume of the container, the pressure of the gas will increase. If we increase the volume of the container, the pressure of the gas will decrease.