Question

A stream moving with a speed of 7.1 m/s reaches a point where the cross-sectional area of the stream decreases to one half of the original area. What is the speed of the water in this narrowed portion of the stream?

Answer 1

14.2 m/s

Step-by-step explanation:

Given data:

Speed of the stream, v₁ = 7.1 m/s

let the cross section area at initial point be A₁

now area at the second point, A₂ = (1/2)A₁ = 0.5A₁

now, from the continuity equation, we have

A₁v₁ = A₂v₂

where, v₂ is the velocity at the narrowed portion

thus, on substituting the values, we get

A₁ × 7.1 = 0.5A₁ × v₂

or

v₂ = 14.2 m/s