And the expansion creates a larger D or a larger volume. And because this guy is constant, this must be constant. So an increase in D must mean a decrease in P. A decrease in P will decrease. Obviously, this P, and look, p, or pressure, is equal to force comes area. Area remains constant, because if you take the cross sectional area of this cylinder, it doesn't change as the piston moves up or down. So if this guy is constant and this guy is decreasing, the pressure is decreasing, then the force must also decrease.