What causes water to flow faster through a pipe?

Water flows faster through a narrow area of a pipe due to the principle of continuity in fluid dynamics. According to this principle, when a fluid flows through a pipe that changes in diameter, the velocity of the fluid must increase in narrower sections to maintain a constant flow rate. This is because the same volume of water must pass through each cross-section of the pipe over a given period of time.

When the cross-sectional area of the pipe decreases, the speed of the water must increase to ensure that the same amount of water moves through per unit time. This is mathematically described by the continuity equation, which states that the product of the cross-sectional area and the fluid velocity remains constant along a streamline.

In contrast, wider areas of the pipe would lead to a slower flow speed, as the same volume of water would have more area to occupy, thus reducing its velocity. The temperature of the water can affect its viscosity but does not directly change the flow speed based on the size of the pipe. Similarly, the length of the pipe can create resistance due to friction but does not inherently cause faster flow as a narrower diameter would.