Question

A stream moving with 2 m/s reaches a point where the cross-section area of the stream decreases to one-fourth of the original area. What is the water speed in this narrowed portion of the stream?

Answer 1

Given,

Initial speed is v=2 m/s

The cross sectional area reduces to 1/4 of the original area

To find

The speed of water at the narrowed portion.

Explanation

Let the original area be A

Let the speed at the narrowed portion be u

By conservation lawwe have,

$\begin{gathered} v\times A=u\times\frac{1}{4}A \\ \Rightarrow2\times4=u \\ \Rightarrow u=8\text{ m/s} \end{gathered}$

Conclusion

The speed at the narrowed portion is 8 m/s