Q1.
You must have seen water spurting out like a fountain from leaking joints or holes in water pipes. Can you explain why this happens? Is it due to the pressure exerted by water on the walls of the pipes?
Answer
Yes — it is the pressure of the water on the pipe wall that drives the fountain.
Water in a supply pipe is under pressure, because the pipe is fed from a tank standing high above it. That water presses outwards on the pipe wall everywhere, exactly as it pressed on the wall of the bottle in Activity 6.2. Where the wall is unbroken, the metal or plastic pushes back and holds the water in. At a crack or a loose joint there is nothing to push back, so the water is driven out through the gap.
Why it shoots up: the opening is small, so all the water forced out has to pass through a tiny area at high speed, and it leaves in whatever direction the hole faces. The taller the tank feeding the pipe, the greater the pressure and the higher the fountain — another sign that liquid pressure depends on the height of the column above.