One section of a pipe carrying water has a cross-sectional area of 16 cm2; in this section the water has flow velocity of 1.0 m/s. another section of this pipe has a constricted cross-sectional area of 4 cm2. if the flow is steady, what is the water velocity in the constricted section?
(a) 4.0 m/s
(b) 2.0 m/s
(c) 1.0 m/s
(d) 0.50 m/s
(e) 0.25 m/s.

Explanation:

For steady state we have discharge(Q) at all points are same.

             Q₁ = Q₂

We know

          Discharge = Area x Velocity

           Q =A v

So we have

           A₁ v₁ = A₂v₂

Given that

           A₁ = 16 cm²

           v₁ = 1 m/s

           A₂ = 4 cm²

           v₂ = ?

Substituting

             16 x 1 = 4 x v₂          

              v₂ = 4 m/s

Option A is the correct answer.