Take a large piston or sealed syringe and stand it on end, then place an increasing number of objects on top. As the pressure grows, the volume of the air inside will decrease—these quantities are inversely proportional. At the start, it is relatively easy to push the piston down, but as we apply a greater pressure, it becomes increasingly difficult to compress the air inside. Measuring the cross sectional area of the piston, the total weight exerted, and the volume, Boyle's law, , can be validated. The plot represents this behavior quantitatively. For simplicity, magnitudes of the variables are chosen equal to 1 initially.