When there is constant flow in a pipe, what happens to the velocity of gas when the pipe size increases?

When there is a constant flow in a pipe, an increase in the pipe's diameter results in a decrease in the velocity of the gas. This behavior is explained by the principle of continuity in fluid dynamics, which states that for an incompressible fluid flowing through a pipe system, the product of the cross-sectional area and the fluid velocity must remain constant.

As the diameter of the pipe increases, the cross-sectional area increases as well. Because the flow rate (volume per unit time) remains constant, the velocity must adjust downwards to accommodate the larger area. This relationship can be understood through the equation of continuity:

Flow rate = Velocity × Cross-sectional area.

If the cross-sectional area increases due to a larger pipe size, the velocity of the gas must decrease proportionally to maintain the same flow rate.

In summary, the correct choice indicates that with a constant flow in a larger diameter pipe, the gas velocity decreases, which aligns with fluid dynamics principles.