Sometimes you see a fountain of water rushing out of the leaking joints (or holes) in the pipes of main water supply line in the city. Why does it happen?

Explanation

**Step-by-Step Solution:**

1. **Understanding Pressure in Fluids:**
- In fluids, pressure is defined as the force exerted per unit area. In the case of water in pipes, the water exerts pressure on the walls of the pipes due to its weight and the force applied by the water above it.

2. **Identifying the Source of Pressure:**
- The water supply line in a city is usually under high pressure to ensure that water can reach homes and businesses effectively. This pressure is created by pumps and the gravitational force acting on the water in elevated reservoirs.

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