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Fluids Formula

What is Continuity Equation?

For an incompressible fluid, the volume flow rate is constant along a pipe — narrow sections mean faster flow.

Formula: A_1 v_1 = A_2 v_2

Plain-English Meaning

For an incompressible fluid, the volume flow rate is constant along a pipe — narrow sections mean faster flow.

Mechanics questions usually become easier once you identify whether the problem is about force balance, kinematics, energy, or conservation.

Deeper Explanation

For an incompressible fluid, the volume flow rate is constant along a pipe — narrow sections mean faster flow.

Worked Example

Problem: Water flows through a pipe of area 0.01 m² at 2 m/s. It narrows to 0.005 m². Find the exit speed.

  • A₁v₁ = A₂v₂
  • 0.01 × 2 = 0.005 × v₂
  • v₂ = 0.02 / 0.005 = 4 m/s

Result: 4 m/s

At A Glance

Category: Fluids

Levels covered:

Best use: Start with the formula meaning, then move to the worked example and quiz so the equation turns into a tool instead of a memorised line.